Therapeutic furopyrimidines and thienopyrimidines

ABSTRACT

The invention provides compounds of formula I, II, and III as described herein, as well as pharmaceutical compositions comprising the compounds, and synthetic methods and intermediates that are useful for preparing the compounds. The compounds of formula I, II, and III are useful as anti-viral agents and/or as anti-cancer agents.

PRIORITY

This application is a continuation of international patent applicationnumber PCT/US2005/039072, filed 28 Oct. 2005; this application alsoclaims priority from U.S. Provisional Patent Application Nos.60/623,065, filed Oct. 29, 2004; 60/641,754, filed Jan. 7, 2005;60/665,832, filed Mar. 29, 2005; and 60/692,572, filed Jun. 22, 2005.

BACKGROUND OF THE INVENTION

Viral diseases are a major cause of death and economic loss in theworld. The Flaviviridae family of viruses consists of three genera: theflaviviruses (including dengue, West Nile, and yellow fever viruses),hepacivirus (HCV), and the pestiviruses (including bovine viral diarrheavirus, BVDV). The disease states and conditions caused by members ofthis family include yellow fever, dengue, Japanese encephalitis, St.Louis encephalitis, Hepatitis B and C, West Nile disease, and AIDS.Currently, human immunodeficiency virus (HIV), hepatitis B virus (HBV)and hepatitis C virus (HCV) infections are responsible for the largestnumber of viral related deaths worldwide. Although there are some drugsuseful for treating HIV, there are only a few drugs useful for treatingHBV, and no drugs that are broadly useful for treating HCV.

Ribavirin (1-β-D-ribofuranosyl-1-1,2,4-triazole-3-carboxamide) is asynthetic, non-interferon-inducing, broad spectrum antiviral nucleoside.Ribavirin is structurally similar to guanosine, and has in vitroactivity against several DNA and RNA viruses including Flaviviridae(Davis. Gastroenterology 118:S104-S114, 2000). Ribavirin reduces serumamino transferase levels to normal in 40% of patients, but it does notlower serum levels of HCV-RNA (Davis. Gastroenterology 118:S104-S114,2000). Thus, ribavirin alone is not effective in reducing viral RNAlevels. Additionally, ribavirin has significant toxicity and is known toinduce anemia.

Interferons (IFNs) are compounds which have been commercially availablefor the treatment of chronic hepatitis for nearly a decade. IFNs areglycoproteins produced by immune cells in response to viral infection.IFNs inhibit viral replication of many viruses, including HCV. When usedas the sole treatment for hepatitis C infection, IFN suppresses serumHCV-RNA to undetectable levels. Additionally, IFN normalizes serum aminotransferase levels. Unfortunately, the effects of IFN are temporary anda sustained response occurs in only 8%-9% of patients chronicallyinfected with HCV (Davis. Gastroenterology 118:S104-S114, 2000).

HCV is a positive stranded ss RNA virus with a well characterizedRNA-dependent RNA polymerase (RdRp) and a well characterized diseaseprogression. HCV has infected an estimated 170 million people worldwide,leading to a major health crisis as a result of the disease. Indeed,during the next few years the number of deaths from HCV-related liverdisease and hepatocellular carcinoma may overtake those caused by AIDS.Egypt is the hardest hit country in the world, with 23% of thepopulation estimated to be carrying the virus; whereas, in the USA theprevalence of chronic infections has recently been determined to bearound 1.87% (2.7 million persons). HCV infections become chronic inabout 50% of cases. Of these, about 20% develop liver cirrhosis that canlead to liver failure, including hepatocellular carcinoma.

The NS5B region of HCV encodes a 65 KDa RdRp thought to be responsiblefor viral genome replication. RdRps function as the catalytic subunit ofthe viral replicase required for the replication of all positive-strandviruses. The NS5B protein has been well characterized, shown to possessthe conserved GDD motif of RdRps and in vitro assay systems have beenreported. Cellular localization studies revealed that NS5B ismembrane-associated in the endoplasmic reticulum like NS5A, suggestingthat those two proteins may remain associated with one another afterproteolytic processing. Additional evidence suggests that NS3, NS4A andNS5B interact with each other to form a complex that functions as partof the replication machinery of HCV.

The X-ray crystal structure of NS5B apoenzyme has been determined andthree very recent publications describe the unusual shape of themolecule. This unique shape for a polymerase, resembling a flat sphere,is attributed to extensive interactions between the fingers and thumbsubdomains in such a way that the active site is completely encircled,forming a cavity 15 Å across and 20 Å deep. Modeling studies showed thatthe NS5B apoenzyme can accommodate the template-primer without largemovement of the subdomains, suggesting that the structure is preservedduring the polymerization reaction. The RdRp polypeptides from variousmembers of the Flaviviridae family and other viral families have beenshown to be conserved (J. A. Bruenn, Nucleic Acids Research, Vol. 19,No. 2 p. 217, 1991).

Currently, there are no safe and effective therapeutic agents on themarket that target HCV polymerase. There is currently a need fortherapeutic agents and therapeutic methods that are useful for treatingviral infections, such as HCV, HIV, and HBV.

In addition, there is also a current need for therapeutic agents andtherapeutic methods that are useful for treating cancer. Even thoughsignificant advances have occurred in the treatment of cancer, it stillremains a major health concern. It has been reported that cancer is thecause of death of up to one of every four Americans. Notwithstanding theadvances in treatments for cancer and other diseases there is still aneed for novel drugs that are effective to treat cancer.

SUMMARY OF THE INVENTION

The present invention provides compounds that are inhibitors of viralRNA and DNA polymerases (e.g. polymerases from hepatitis B, hepatitis C,human immunodeficiency virus, Polio, Coxsackie A and B, Rhino, Echo,small pox, Ebola, and West Nile virus) and that are useful for treatingHCV, as well as other viral infections (e.g. flaviviral infections), andcancer.

Accordingly, the invention provides novel compounds of formulae I, II,and III as described herebelow, or a pharmaceutically acceptable salt orprodrug thereof.

The invention also provides a pharmaceutical composition comprising acompound of formula I, II, or III, or a pharmaceutically acceptable saltor prodrug thereof, and a pharmaceutically acceptable carrier. Thecomposition can optionally comprise one or more additional anti-viral oranti-cancer agents.

The invention also provides a method for treating a viral infection inan animal comprising administering to the animal an effective amount ofa compound of formula I, II, or III, or a pharmaceutically acceptablesalt or prodrug thereof.

The invention also provides a method for inhibiting a viral RNA or DNApolymerase comprising contacting the polymerase (in vitro or in vivo)with an effective inhibitory amount of a compound of formula I, II, orIII, or a pharmaceutically acceptable salt or prodrug thereof.

The invention also provides a method for treating cancer in an animalcomprising administering to the animal an effective amount of a compoundof formula I, II, or III, or a pharmaceutically acceptable salt orprodrug thereof.

The invention also provides a compound of formula I, II, or III, or apharmaceutically acceptable salt or prodrug thereof, for use in medicaltherapy (e.g. for use in treating a viral infection or for use intreating cancer).

The invention also provides the use of a compound of formula I, II, orIII, or a pharmaceutically acceptable salt or prodrug thereof, toprepare a medicament useful for treating a viral infection in an animal(e.g. a human).

The invention also provides the use of a compound of formula I, II, orIII, or a pharmaceutically acceptable salt or prodrug thereof, toprepare a medicament useful for treating cancer in an animal (e.g. ahuman).

The invention also provides novel synthetic intermediates and syntheticmethods that are disclosed herein as being useful for preparingcompounds of formula I, II, or III. Some compounds of formula I, II, andIII may be useful as synthetic intermediates for preparing othercompounds of formula I, II, and III.

DETAILED DESCRIPTION OF THE INVENTION

Definitions

The term “pharmaceutically acceptable salt” as used herein refers to acompound of the present disclosure derived from pharmaceuticallyacceptable bases, inorganic or organic acids. Examples of suitable acidsinclude, but are not limited to, hydrochloric, hydrobromic, sulfuric,nitric, perchloric, fumaric, maleic, phosphoric, glycollic, lactic,salicyclic, succinic, toluene-p-sulfonic, tartaric, acetic, citric,methanesulfonic, formic, benzoic, malonic, naphthalene-2-sulfonic,trifluoroacetic and benzenesulfonic acids. Salts derived fromappropriate bases include, but are not limited to, alkali such as sodiumand ammonia.

The terms “treat”, “treating” and “treatment” as used herein includeadministering a compound prior to the onset of clinical symptoms of adisease state/condition so as to prevent any symptom, as well asadministering a compound after the onset of clinical symptoms of adisease state/condition so as to reduce or eliminate any symptom, aspector characteristic of the disease state/condition. Such treating need notbe absolute to be useful.

The term “animal” as used herein refers to any animal, includingmammals, such as, but not limited to, mice, rats, other rodents,rabbits, dogs, cats, swine, cattle, sheep, horses, and primates. In onespecific embodiment of the invention the animal is a human.

The term “therapeutically effective amount”, in reference to treating adisease state/condition, refers to an amount of a compound either aloneor as contained in a pharmaceutical composition that is capable ofhaving any detectable, positive effect on any symptom, aspect, orcharacteristics of a disease state/condition when administered as asingle dose or in multiple doses. Such effect need not be absolute to bebeneficial.

The term “alkyl” as used herein refers to alkyl groups having from 1 to6 carbon atoms. This term is exemplified by groups such as methyl,ethyl, n-propyl, iso-propyl, n-butyl, t-butyl, n-pentyl and the like. Ina specific embodiment, the alkyl groups have from 1-4 carbon atoms andare referred to as lower alkyl.

The term “substituted alkyl” as used herein refers to an alkyl grouphaving from 1 to 3 substituents, said substituents being selected fromthe group consisting of alkoxy, substituted alkoxy, acyl, substitutedacyl, acylamino, acyloxy, oxyacyl, amino, substituted amino, aminoacyl,aryl, substituted aryl, aryloxy, substituted aryloxy, cyano, halogen,hydroxyl, nitro, N₃, carboxyl, carboxyl esters, thiol, thioalkyl,substituted thioalkyl, thioaryl, substituted thioaryl, thioheteroaryl,substituted thioheteroaryl, thiocycloalkyl, substituted thiocycloallcyl,thioheterocyclic, substituted thioheterocycliccycloalkyl, substitutedcycloalkyl, heteroaryl, substituted heteroaryl, heterocyclic, andsubstituted heterocyclic.

The terms “alkenyl” or “alkene” as used herein refers to an alkenylgroup having from 2 to 10 carbon atoms and having at least 1 site ofalkenyl unsaturation. Such groups are exemplified by vinyl(ethen-1-yl),allyl, but-3-en-1-yl, and the like.

The term “substituted alkenyl” as used herein refers to alkenyl groupshaving from 1 to 3 substituents, said substituents being selected fromthose describe above for a substituted alkyl.

The term “alkynyl” or “alkyne” as used herein refers to an alkynyl grouphaving from 2-10 carbon atoms and having at least 1 site of alkynylunsaturation. Such groups are exemplified by, but not limited to,ethyn-1-yl, propyn-1-yl, propyn-2-yl, 1-methylprop-2-yn-1-yl,butyn-1-yl, butyn-2-yl, butyn-3-yl, and the like.

The term “substituted alkynyl” as used herein refers to alkynyl groupshaving from 1 to 3 substituents, said substituents being selected thosedescribe above for a substituted alkyl.

The term “alkoxy” refers to the group alkyl-O—.

The term “substituted alkoxy” as used herein refers to the groupsubstituted alkyl-O—.

The term “acyl” as used herein refers to the groups alkyl-C(O)—,alkenyl-C(O)-alkynyl-C(O)—, cycloalkyl-C(O)—, aryl-C(O)—,heteroaryl-C(O)—, and heterocyclic-C(O).

The term “substituted acyl” as used herein refers to the groupssubstituted alkyl-C(O)—, substituted alkenyl-C(O)—, substitutedalkynyl-C(O)—, substituted cycloalkyl-C(O)—, substituted aryl-C(O)—,substituted heteroaryl-C(O), and substituted heterocyclic-C(O)—.

The term “acylamino” as used herein refers to the group-C(O)NZ₁Z₂ whereeach Z₁ and Z₂ are independently selected from the group consisting ofhydrogen, alkyl, substituted alkyl, alkenyl, substituted alkenyl,alkynyl and substituted alkynyl, and the substituents described above inthe definition of substituted alkyl.

The term “acyloxy” as used herein refers to the groups alkyl-C(O)O—,substituted alkyl-C(O)O—, alkenyl-C(O)O—, substituted alkenyl-C(O)O—,alkynyl-C(O)O—, substituted alkynyl-C(O)O—, aryl-C(O)O—, substitutedaryl-C(O)O—, cycloalkyl-C(O)O—, substituted cycloalkyl-C(O)O—,heteroaryl-C(O)O—, substituted heteroaryl-C(O)O—, heterocyclic-C(O)O—,and substituted heterocyclic-C(O)O—.

The term “oxyacyl” as used herein refers to the groups alkyl-OC(O)—,substituted alkyl-OC(O)—, alkenyl-OC(O)—, substituted alkenyl-OC(O)—,alkynyl-OC(O)—, substituted alkynyl-OC(O)—, aryl-OC(O)—, substitutedaryl-OC(O)—, cycloalkyl-OC(O)—, substituted cycloalkyl-OC(O)—,heteroaryl-OC(O)—, substituted heteroaryl-OC(O)—, heterocyclic-OC(O)—,and substituted heterocyclic-OC(O)—.

The term “amino” as used herein refers to the group —NH₂.

The term “substituted amino” as used herein refers to the group-N Z₁Z₂where Z₁ and Z₂ are as described above in the definition of acylamino,provided that Z₁ and Z₂ are both not hydrogen.

The term “aminoacyl” as used herein refers to the groups —NZ₃C(O)alkyl,—NZ₃C(O)substituted alkyl, —NZ₃C(O)cycloalkyl, —NZ₃C(O)substitutedcycloalkyl, —NZ₃C(O)alkenyl, —NZ₃C(O)substituted alkenyl,—NZ₃C(O)alkynyl, —NZ₃C(O)substituted alkynyl, —NZ₃C(O)aryl,—NZ₃C(O)substituted aryl, —NZ₃C(O)heteroaryl, —NZ₃C(O)substitutedheteroaryl, —NZ₃C(O)heterocyclic, and —NZ₃C(O)substituted heterocyclic,where NZ₃ is hydrogen or alkyl.

The term “aryl” as used herein refers to a monovalent aromatic cyclicgroup of from 6 to 14 carbon atoms having a single ring (e.g., phenyl)or multiple condensed rings (e.g., naphthyl or anthryl) which condensedrings may or may not be aromatic. Exemplary aryls include, but are notlimited to, phenyl and naphthyl.

The term “substituted aryl” as used herein refers to aryl groups whichare substituted with from 1 to 3 substituents selected from alkyl,substituted alkyl, alkenyl, substituted alkenyl, alkynyl and substitutedalkynyl, and those substituents described above in the definition ofsubstituted alkyl.

The term “aryloxy” as used herein refers to the group aryl-O— thatincludes, by way of example but not limitation, phenoxy, naphthoxy, andthe like.

The term “substituted aryloxy” as used herein refers to substitutedaryl-O-groups.

The term “carboxyl” as used herein refers to —COOH or salts thereof.

The term “carboxyl esters” as used herein refers to thegroups-C(O)O-alkyl, —C (O)O-substituted alkyl, —C(O)O-aryl, and—C(O)O-substituted aryl

The term “cycloalkyl” as used herein refers to a saturated orunsaturated cyclic hydrocarbon ring systems, such as those containing 1to 3 rings and 3 to 7 carbons per ring. Exemplary groups include but arenot limited to cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl,cycloheptyl, and adamantyl.

The term “substituted cycloalkyl” as used herein refers to a cycloalkylhaving from 1 to 5 substituents selected from the group consisting ofoxo (═O), thioxo (═S), alkyl, substituted alkyl, and those substituentsdescribed in the definition of substituted alkyl.

The term “cycloalkoxy” as used herein refers to —O-cycloalkyl groups.

The term “substituted cycloalkoxy” as used herein refers to—O-substituted cycloalkyl groups.

The term “formyl” as used herein refers to HC(O)—.

The term “halogen” as used herein refers to fluoro, chloro, bromo andiodo.

The term “heteroaryl” as used herein refers to an aromatic group of from1 to 10 carbon atoms and 1 to 4 heteroatoms selected from the groupconsisting of oxygen, nitrogen, sulfur in the ring. The sulfur andnitrogen heteroatoms atoms may also be present in their oxidized forms.Such heteroaryl groups can have a single ring (e.g., pyridyl or furyl)or multiple condensed rings (e.g., indolizinyl or benzothienyl) whereinthe condensed rings may or may not be aromatic and/or contain aheteroatom. Exemplary heteroaryl groups include, but are not limited to,heteroaryls include pyridyl, pyrrolyl, thienyl, indolyl, thiophenyl, andfuryl.

The term “substituted heteroaryl” as used herein refers to heteroarylgroups that are substituted with from 1 to 3 substituents selected fromthe same group of substituents defined for substituted aryl.

The term “heteroaryloxy” as used herein refers to the group—O-heteroaryl.

The term “substituted heteroaryloxy” as used herein refers to the group—O-substituted heteroaryl.

The term “heterocycle” or “heterocyclic” or “heterocycloalkyl” refers toa saturated or unsaturated group (but not heteroaryl) having a singlering or multiple condensed rings, from 1 to 10 carbon atoms and from 1to 4 hetero atoms selected from the group consisting of nitrogen,oxygen, sulfur, within the ring wherein, in fused ring systems, one ormore the rings can be cycloalkyl, aryl or heteroaryl provided that thepoint of attachment is through the heterocyclic ring. The sulfur andnitrogen heteroatoms atoms may also be present in their oxidized forms.

The term “substituted heterocycle” or “substituted heterocyclic” or“substituted heterocycloalkyl” refers to heterocycle groups that aresubstituted with from 1 to 3 of the same substituents as defined forsubstituted aryl.

Examples of heterocycles and heteroaryls include, but are not limitedto, azetidine, pyrrole, imidazole, pyrazole, pyridine, pyrazine,pyrimidine, pyridazine, indolizine, isoindole, indole, dihydroindole,indazole, purine, quinolizine, isoquinoline, quinoline, phthalazine,naphthylpyridine, quinoxaline, quinazoline, cinnoline, pteridine,carbazole, carboline, phenanthridine, acridine, phenanthroline,isothiazole, phenazine, isoxazole, phenoxazine, phenothiazine,imidazolidine, imidazoline, piperidine, piperazine, indoline,phthalimide, 1,2,3,4-tetrahydroisoquinoline,4,5,6,7-tetrahydrobenzo[b]thiophene, thiazole, thiazolidine, thiophene,benzo[b]thiophene, morpholinyl, thiomorpholinyl (also referred to asthiamorpholinyl), piperidinyl, pyrrolidine, tetrahydrofuranyl, and thelike.

The term “heterocyclyloxy” as used herein refers to the group—O-heterocyclic.

The term “substituted heterocyclyloxy” as used herein refers to thegroup-O-substituted heterocyclic.

The term “phosphate” as used herein refers to the groups—OP(O)(OH)₂(monophosphate or phospho), —OP(O)(OH)OP(O)(OH)₂ (diphosphate ordiphospho) and —OP(O)(OH)OP(O)(OH)OP(O)(OH)₂ (triphosphate ortriphospho) or salts thereof including partial salts thereof. It isunderstood that the initial oxygen of the mono-, di-, and triphosphatemay include the oxygen atom of a sugar.

The term “phosphate esters” as used herein refers to the mono-, di- andtri-phosphate groups described above wherein one or more of the hydroxylgroups is replaced by an alkoxy group.

The term “phosphonate” refers to the groups —OP(O)(Z₄)(OH) or —OP(O)(Z₄)(OZ₄) or salts thereof including partial salts thereof, wherein eachZ₄ is independently selected from hydrogen, alkyl, substituted alkyl,carboxylic acid, and carboxyl ester. It is understood that the initialoxygen of the phosphonate may include the oxygen of a sugar.

The term “thiol” as used herein refers to the group —SH.

The term “thioalkyl” or “alkylthioether” or “thioalkoxy” refers to thegroup—S-alkyl.

The term “substituted thioalkyl” or “substituted alkylthioether” or“substituted thioalkoxy” refers to the group —S-substituted alkyl.

The term “thiocycloalkyl” as used herein refers to the group—S-cycloalkyl.

The term “substituted thiocycloalkyl” as used herein refers to the group—S-substituted cycloalkyl.

The term “thioaryl” as used herein refers to the group —S-aryl.

The term “substituted thioaryl” as used herein refers to thegroup-S-substituted aryl.

The term “thioheteroaryl” as used herein refers to the group—S-heteroaryl.

The term “substituted thioheteroaryl” as used herein refers to the group—S-substituted heteroaryl.

The term “thioheterocyclic” as used herein refers to the group—S-heterocyclic.

The term “substituted thioheterocyclic as used herein refers to thegroup —S-substituted heterocyclic.

The term “amino acid sidechain” refers to the Z₇ substituent of α-aminoacids of the formula Z₆NHCH(Z₇)COOH where Z₇ is selected from the groupconsisting of hydrogen, alkyl, substituted alkyl and aryl and Z₆ ishydrogen or together with Z₇ and the nitrogen and carbon atoms boundthereto respectively form a heterocyclic ring. In one embodiment, theα-amino acid sidechain is the sidechain one of the twenty naturallyoccurring L amino acids.

Sugars described herein may either be in D or L configuration.

Compounds of Formula I

Compounds of the invention include compounds of formula I:

wherein:

Y is O or S;

R is OR₃, SR₃, NR₃R₄, NR₃NR₄R₅, alkyl, substituted alkyl, alkenyl,substituted alkenyl, alkynyl, substituted alkynyl, aryl, substitutedaryl, (CH₂)_(n)—CH(NHR₃)CO₂R₄, Cl, F, Br, I, CN, COOR₃, CONR₃R₄,NHC(═NR₃)NHR₄, NR₃OR₄, NR₃NO, NHCONHR₃, NR₃N═NR₄, NR₃N═CHR₄,NR₃C(O)NR₄R₅, NR₃C(S)NR₄R₅, NR₃C(O)OR₄, CH═N—OR₃, NR₃C(═NH)NR₄R₅,NR₃C(O)NR₄NR₅R₆, O—C(O)R₃, OC(O)—OR₃, ONH—C(O)O-alkyl, ONHC(O)O-aryl,ONR₃R₄, SNR₃R₄, S—ONR₃R₄, or SO₂NR₃R₄;

n is 0-5;

R¹ is H, NR₃R₄, Cl, F, OR₃, SR₃, NHCOR₃, NHSO₂R₃, NHCONHR₃, CN, alkyl,aryl, ONR₃R₄, or NR₃C(O)OR₄;

R² is a nucleoside sugar group; and

R₃, R₄, R₅, and R₆ are independently selected from the group consistingof H, alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl,substituted alkynyl, cycloalkyl, heterocyclic, aryl, substituted aryl,acyl, substituted acyl, SO₂-alkyl and NO; or R₃ and R₄ together with thenitrogen to which they are attached form a pyrrolidino, piperidino,piperazino, azetidino, morpholino, or thiomorpholino ring; or R₄ and R₅together with the nitrogen to which they are attached form apyrrolidino, piperidino, piperazino, azetidino, morpholino, orthiomorpholino ring;

or a pharmaceutically acceptable salt or prodrug thereof;

U.S. Pat. No. 4,584,369 relates to certain specific nucleosides.Accordingly, in one embodiment, the invention excludes compounds offormula I wherein Y is S; when R is —NH₂, —OH, —SH, or —SCH₃; R¹ ishydrogen; and R² is non-phosphorylated ribose; as well as compounds offormula I wherein Y is O; when R is —NH₂; R¹ is hydrogen; and R² isnon-phosphorylated ribose.

In another embodiment the invention excludes compounds of formula Iwherein Y is S; R is —NH₂, —OH, —SH, or —SCH₃; R¹ is hydrogen; and R² isribose; as well as compounds of formula I wherein Y is O; R is —NH₂; R¹is hydrogen; and R² is ribose.

In another embodiment, the invention excludes compounds of formula Iwherein R is —SH, —OH, —S-alkyl, —O-alkyl, or NR₃R₄; R₃ and R₄ are eachH or alkyl; and R² has the following formula:

wherein: one of R³⁰⁰ and R³⁰⁴ is H and the other is H or OH; R³⁰² is OH,alkyl-O—, alkylC(═O)O—, alkyl-S—, or alkylC(═O)—S—; R³⁰³ is H; and Z³⁰⁰is OH, alkyl-O—, alkylC(═O)O—, alkyl-S—, or alkylC(═O)—S—.

In another embodiment, the invention excludes compounds of formula Iwherein R² has the following formula:

wherein: one of R³⁰⁰ and R³⁰⁴ is H and the other is H or OH; R³⁰² is OH,alkyl-O—, alkylC(═O)O, alkyl-S—, or -alkylC(═O)—S—; R³⁰³ is H; and Z³⁰⁰is OH, alkyl-O—, alkylC(═O)O, alkyl-S—, or alkylC(═O)—S—.

In one embodiment the invention provides a compound of formula I asdescribed above, wherein Y is O; or a pharmaceutically acceptable saltor prodrug thereof.

In one embodiment the invention provides a compound of formula I asdescribed above, wherein Y is S; or a pharmaceutically acceptable saltor prodrug thereof.

In one embodiment the invention provides a compound of formula I asdescribed above, wherein R is OR₃, Cl, SR₃, NR₃R₄, or NR₃NR₄R₅; or apharmaceutically acceptable salt or prodrug thereof.

In one embodiment the invention provides a compound of formula I asdescribed above, wherein R is NR₃R₄; R₃ is selected from the groupconsisting of H, alkyl, substituted alkyl, alkenyl, substituted alkenyl,alkynyl, substituted alkynyl, cycloalkyl, heterocyclic, aryl,substituted aryl, acyl, substituted acyl, SO₂-alkyl and NO; and R₄ isselected from the group consisting of H, alkyl, substituted alkyl,alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, cycloalkyl,heterocyclic, aryl, substituted aryl, acyl, substituted acyl, SO₂-alkyland NO; or R₃ and R₄ together with the nitrogen to which they areattached form a pyrrolidino, piperidino, piperazino, azetidino,morpholino, or thiomorpholino ring; or R₄ and R₅ together with thenitrogen to which they are attached form a pyrrolidino, piperidino,piperazino, azetidino, morpholino, or thiomorpholino ring.

In one embodiment the invention provides a compound of formula I asdescribed above, wherein R is NR₃NR₄R₅, alkyl, substituted alkyl,alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, aryl,substituted aryl, (CH₂)_(n)—CH(NHR₃)CO₂R₄, Cl, F, Br, I, CN, COOR₃,CONR₃R₄, NHC(═NR₃)NHR₄, NR₃OR₄, NR₃NO, NHCONHR₃, NR₃N═NR₄, NR₃N═CHR₄,NR₃C(O)NR₄R₅, NR₃C(S)NR₄R₅, NR₃C(O)OR₄, CH═N—OR₃, NR₃C(═NH)NR₄R₅,NR₃C(O)NR₄NR₅R₆, O—C(O)R₃, OC(O)—OR₃, ONH—C(O)O-alkyl, ONHC(O)O-aryl,ONR₃R₄, SNR₃R₄, S—ONR₃R₄, or SO₂NR₃R₄.

In one embodiment the invention provides a compound of formula I asdescribed above, wherein R₁ is H or NR₃R₄; or a pharmaceuticallyacceptable salt or prodrug thereof.

In one embodiment the invention provides a compound of formula I asdescribed above, wherein R² is a nucleoside sugar group of Group A, B,C, D, E, or F described hereinbelow; or a pharmaceutically acceptablesalt or prodrug thereof.

In another embodiment the invention provides a compound of formula I asdescribed above, wherein R² is ribose, 2-deoxyribose;2-deoxy-2-fluororibose; arabinose; 2-deoxy-2-fluoroarabinose;2,3-dideoxyribose; 2,3-dideoxy-2-fluoroarabinose;2,3-dideoxy-3-fluororibose; 2,3-dideoxy-2,3-didehydroribose;2,3-dideoxy-3-azidoribose; 2,3-dideoxy-3-thiaribose; or2,3-dideoxy-3-oxaribose; or a pharmaceutically acceptable salt orprodrug thereof.

In another embodiment the invention provides a compound of formula I asdescribed above, wherein R² is ribose, 2-methylribose, 2-deoxyribose;2-deoxy-2-fluororibose; arabinose; 2-deoxy-2-fluoroarabinose;2,3-dideoxyribose; 2,3-dideoxy-2-fluoroarabinose;2,3-dideoxy-3-fluororibose; 2,3-dideoxy-2,3-didehydroribose;2,3-dideoxy-3-azidoribose; 2,3-dideoxy-3-thiaribose; or2,3-dideoxy-3-oxaribose; or a pharmaceutically acceptable salt orprodrug thereof.

In another embodiment the invention provides a compound of formula I asdescribed above, wherein R² is thioribose, 2-deoxythioribose;2-deoxy-2-fluorothioribose; thioarabinose;2-deoxy-2-fluorothioarabinose; 2,3-dideoxythioribose;2,3-dideoxy-2-fluorothioarabinose; 2,3-dideoxy-3-fluorothioribose;2,3-dideoxy-2,3-didehydrothioribose; or 2,3-dideoxy-3-azidothioribose;or a pharmaceutically acceptable salt or prodrug thereof.

In another embodiment the invention provides a compound of formula I asdescribed above, wherein R² is 4-hydroxymethylcyclopent-2-ene;2,3-dihydroxy-4-hydroxymethylcyclopent-4-ene;3-hydroxy-4-hydroxymethylcyclopentane;2-hydroxy-4-hydroxymethylcyclopentene;2-fluoro-3-hydroxy-4-hydroxymethylcyclopentane;2,3-dihydroxy-4-hydroxymethyl-5-methylenecyclopentane;4-hydroxymethylcyclopentane, 2,3-dihydroxy-4-hydroxymethylcyclopentane;or 2,3-dihydroxymethylcyclobutane; or a pharmaceutically acceptable saltor prodrug thereof.

In another embodiment the invention provides a compound of formula I asdescribed above, wherein R² is 4-hydroxymethylpyrrolidine;2,3-dihydroxy-4-hydroxymethylpyrrolidine;2/3-hydroxy-4-hydroxymethylpyrrolidine;2-fluoro-3-hydroxy-4-hydroxymethylpyrrolidine; or3-fluoro-2-hydroxy-4-hydroxymethylpyrrolidine; or a pharmaceuticallyacceptable salt or prodrug thereof.

In another embodiment the invention provides a compound of formula I asdescribed above, wherein R₃, R₄, R₅, and R₆ are independently selectedfrom the group consisting of H, alkyl, and substituted alkyl; or R₃ andR₄ together with the nitrogen to which they are attached form apyrrolidino, piperidino, piperazino, azetidino, morpholino, orthiomorpholino ring; or R₄ and R₅ together with the nitrogen to whichthey are attached form a pyrrolidino, piperidino, piperazino, azetidino,morpholino, or thiomorpholino ring.

Compounds of Formula II

The invention also provides novel compounds of formula II:

wherein:

R¹⁰⁰ is alkyl (1-4 carbon atom), alkenyl, or alkynyl, which R¹⁰⁰ may beunsubstituted or substituted;

R¹⁰¹ is H, alkyl, —C(O)alkyl, or aryl-C(═O)—;

R¹⁰² is H, OH, —Oalkyl, —OC(O)alkyl, aryl-C(═O)—O—, —CH₂OH, CH₂NH₂, N₃,CH₂N₃, or NH₂;

R¹⁰³ is H, OH, or NH₂; provided both R¹⁰² and R¹⁰³ cannot be the samegroup except hydrogen.

R¹⁰⁴ is NR¹¹⁰R¹¹¹, NR¹¹⁰—NR¹¹¹R¹¹², NR¹¹⁰N═NR¹¹¹, NR¹¹⁰N═CHR¹¹¹,NR¹¹⁰N═O, NR¹¹⁰C(O)NR¹¹¹R¹¹², NR¹¹⁰C(S)NR¹¹¹R¹¹², NR¹¹⁰C(═NH)NR¹¹¹R¹¹²,NR¹¹⁰C(O)NR¹¹¹NR¹¹²R¹¹³, NR¹¹⁰R¹¹¹, O—C(O)R¹¹⁰, OC(O)—OR¹¹⁰,O—NH—C(O)Oalkyl, ONHC(O)Oaryl, ONR¹¹⁰R¹¹¹, S—NR¹¹⁰R¹¹¹, S—ONR¹¹⁰R¹¹¹, orSO₂NR¹¹⁰R¹¹¹;

R¹⁰⁵ is H, halogen, N₃, NHC(O)R¹⁰⁶, NR¹¹⁰R¹¹¹, NHSO₂R¹⁰⁶, NHCONHR¹⁰⁶,NH—C(S)NHR¹⁰⁶, CH₂NHR¹⁰⁶, NHNH₂, CN, alkyl, alkynyl, CH₂aryl, OH, orSR¹⁰⁶;

R¹⁰⁶ is H or alkyl;

Z¹⁰⁰ is OH, —O—[P(═O)(OH)O—]_(n)—H, —CH₂—[P(═O)(OH)O—]_(n)—H,—O—P(═O)(R¹⁰⁷)R¹⁰⁸, —CH₂—P(═O)(R¹⁰⁷)R¹⁰⁸, —O—[P(═O)(R¹⁰⁹)O—]_(n)—H, or—CH₂—[P(═O)(R¹⁰⁹)O—]_(n)—H;

R¹⁰⁷ and R¹⁰⁸ in phosphonic acid or phosphoric acid independentlyrepresent a protected or unprotected substituted or unsubstitutedhydroxyl group to be decomposed under physiological conditions;

R¹⁰⁹ is a hydroxyl group that may be protected or substituted with agroup to be decomposed under physiological conditions;

R¹¹⁰, R¹¹¹, R¹¹² and R¹¹³ are independently H, alkyl, substituted alkyl,cycloalkyl, heterocyclic, alkoxy, aryl, substituted aryl, acyl,substituted acyl, SO₂-alkyl, NH₂, OH or NO;

R¹¹⁴ is H, alkyl, substituted alkyl, C(O)R¹⁰⁹, aryl, substituted aryl,or heterocycle;

n is 0-3;

X is O, S, NH, or CH₂;

W is CHR¹¹⁴, N, or CH-halo;

Y is O, S, or NR¹¹⁴; and

or a pharmaceutically acceptable salt or prodrug thereof.

In one embodiment the invention provides a compound of formula II asdescribed above, wherein Y is O or S; or a pharmaceutically acceptablesalt or prodrug thereof.

In another embodiment the invention provides a compound of formula II asdescribed above, wherein R¹⁰¹ is H, alkyl, —C(O)alkyl, or benzoyl; andR¹⁰² is H, OH, Oalkyl, —OC(O)alkyl, benzoyl-O—, —CH₂OH, CH₂NH₂, N₃,CH₂N₃, or NH₂; or a pharmaceutically acceptable salt or prodrug thereof.

In another embodiment the invention provides a compound of formula II asdescribed above, wherein Y is O or S; R¹⁰¹ is H, alkyl, —C(O)alkyl, orbenzoyl; and R¹⁰² is H, OH, Oalkyl, —OC(O)alkyl, benzoyl-O—, —CH₂OH,CH₂NH₂, N₃, CH₂N₃, or NH₂; or a pharmaceutically acceptable salt orprodrug thereof.

In another embodiment the invention provides a compound of formula II asdescribed above, wherein Y is O or S; and W is CR¹¹⁴, N, or C-halo; or apharmaceutically acceptable salt or prodrug thereof.

In another embodiment the invention provides a compound of formula II asdescribed above wherein Y is O or S; Z¹⁰⁰ is OH, —O—[P(═O)(OH)O—]_(n)—H,—CH₂—[P(═O)(OH)O—]_(n)—H, —O—P(═O)(R¹⁰⁷)R¹⁰⁸, —CH₂—P(═O)(R¹⁰⁷)R¹⁰⁸,—O—[P(═O)(R¹⁰⁹)O—]_(n)—H, or —CH₂—[P(═O)(R¹⁰⁹)O—]_(n)—H; and R¹⁰⁷ andR¹⁰⁸ are each H; or a pharmaceutically acceptable salt or prodrugthereof.

In another embodiment the invention provides a compound of formula II asdescribed above wherein Y is O or S; Z¹⁰⁰ is OH, —O—[P(═O)(OH)O—]_(n)—H,—CH₂—[P(═O)(OH)O—]_(n)—H, —O—P(═O)(R¹⁰⁷)R¹⁰⁸, —CH₂—P(═O)(R¹⁰⁷)R¹⁰⁸,—O—[P(═O)(R¹⁰⁹)O—]_(n)—H, or —CH₂—[P(═O)(R¹⁰⁹)O—]_(n)—H; W is CR¹¹⁴, N,or C-halo; and R¹⁰⁷ and R¹⁰⁸ are each H; or a pharmaceuticallyacceptable salt or prodrug thereof.

In another embodiment the invention provides a compound of formula II asdescribed above wherein R¹⁰⁰ is alkyl; R¹⁰¹ is H; R¹⁰² is OH; R¹⁰³ is H;R¹⁰⁴ is NR¹¹⁰R¹¹¹ or NR¹¹⁰—NR¹¹¹R¹¹²; R¹⁰⁵ is H or NH₂; R¹¹⁰, R¹¹¹, R¹¹²and R¹¹³ are independently H, alkyl, substituted alkyl, or cycloalkyl;and Z¹⁰⁰ is OH.

For a compound of formula II, a specific value for R¹⁰⁰ is alkyl.

For a compound of formula II, a specific value for R¹⁰¹ is H.

For a compound of formula II, a specific value for R¹⁰² is OH.

For a compound of formula II, a specific value for R¹⁰³ is H.

For a compound of formula II, a specific value for R¹⁰⁴ is NR¹¹⁰R¹¹¹ orNR¹¹⁰—NR¹¹¹R¹¹².

For a compound of formula II, a specific value for R¹⁰⁵ is H or NH₂.

For a compound of formula II, a specific value for R¹⁰⁷ is OH.

For a compound of formula II, a specific value for R¹⁰⁸ is OH.

For a compound of formula II, a specific value for R¹¹⁰, R¹¹¹, R¹¹² andR¹¹³ are independently H, alkyl, substituted alkyl, or cycloalkyl.

For a compound of formula II, a specific value for Z¹⁰⁰ is OH.

For a compound of formula II, a specific value for Z¹⁰⁰ is—O—[P(═O)(OH)O-]_(n)—H, —O—P(═O)(R¹⁰⁷)R¹⁰⁸, or —O—[P(═O)(R¹⁰⁹)O—]_(n)—H.

For a compound of formula II, a specific value for Z¹⁰⁰ is—CH₂—[P(═O)(R¹⁰⁹)O—]_(n)H.

Compounds of Formula III

The invention also provides novel compounds of formula III:

wherein:

X is N or CH;

Y is O, S or N—R²⁰⁴;

-   -   R²⁰⁰ is OR²⁰⁵, OH, NHR²⁰⁴, NR²⁰⁴R²⁰⁵, NHNHR²⁰⁴, NR²⁰⁴NHR²⁰⁵,        SR²⁰⁵, SH, alkyl, aryl, Cl, NR²⁰⁴OR²⁰⁵, NR²⁰⁴NO, or NHCONHR²⁰⁴;    -   R²⁰¹ is H, NHR²⁰⁴, Cl, F, OR²⁰⁴, SR²⁰⁴, NHCOR²⁰⁴, NHSO₂R²⁰⁴,        NHCONHR²⁰⁴, CN, alkyl, aryl, or NR²⁰⁴R²⁰⁵;    -   R²⁰² is a substituted alkyl, moiety from a sugar with the        proviso that when Y═NH or S and R²⁰⁰ is NH₂, OH, SH, alkylamino,        alkyloxy, or alkylthio, the sugar moiety can not be from ribose        or 2-deoxyribose; a moiety from a thio sugar; hydroxyl        substituted cycloalkanes; or hydroxyl substituted 5-pyrrolidine        moieties;    -   R²⁰³ is H, alkyl, aryl, F, Cl, CN, CO₂H or NH₂;    -   R²⁰⁴ is H, OH, alkyl, aryl, —COO-alkyl, CONH₂, CONH-alkyl,        O—C(O)-alkyl, O—C(O)-aryl or alkoxy; and    -   R²⁰⁵ is alkyl, aryl, OH or alkoxy;

and pharmaceutically acceptable salts thereof and prodrugs thereof.

In one embodiment the invention provides a compound of formula III asdescribed above, wherein Y is O or S; or a pharmaceutically acceptablesalt or prodrug thereof.

In one embodiment the invention provides a compound of formula III asdescribed above, wherein R²⁰⁰ is OR²⁰⁵, NHR²⁰⁴, NR²⁰⁴R²⁰⁵, NHNHR²⁰⁴,NR²⁰⁴NHR²⁰⁵, SR²⁰⁵, alkyl, aryl, Cl, NR²⁰⁴OR²⁰⁵, NR²⁰⁴NO, or NHCONHR²⁰⁴.

In one embodiment the invention provides a compound of formula III asdescribed above, wherein R²⁰² is a nucleoside sugar group; or apharmaceutically acceptable salt or prodrug thereof.

In another embodiment the invention provides a compound of formula IIIas described above, wherein R²⁰² is ribose, 2-deoxyribose;2-deoxy-2-fluororibose; arabinose; 2-deoxy-2-fluoroarabinose;2,3-dideoxyribose; 2,3-dideoxy-2-fluoroarabinose;2,3-dideoxy-3-fluororibose; 2,3-dideoxy-2,3-didehydroribose;2,3-dideoxy-3-azidoribose; 2,3-dideoxy-3-thiaribose; or2,3-dideoxy-3-oxaribose.

In another embodiment the invention provides a compound of formula IIIas described above, wherein R²⁰² is ribose, 2-methylribose,2-deoxyribose; 2-deoxy-2-fluororibose; arabinose;2-deoxy-2-fluoroarabinose; 2,3-dideoxyribose;2,3-dideoxy-2-fluoroarabinose; 2,3-dideoxy-3-fluororibose;2,3-dideoxy-2,3-didehydroribose; 2,3-dideoxy-3-azidoribose;2,3-dideoxy-3-thiaribose; or 2,3-dideoxy-3-oxaribose.

In another embodiment the invention provides a compound of formula IIIas described above, wherein R²⁰² is thioribose, 2-deoxythioribose;2-deoxy-2-fluorothioribose; thioarabinose;2-deoxy-2-fluorothioarabinose; 2,3-dideoxythioribose;2,3-dideoxy-2-fluorothioarabinose; 2,3-dideoxy-3-fluorothioribose;2,3-dideoxy-2,3-didehydrothioribose; or 2,3-dideoxy-3-azidothioribose.

In another embodiment the invention provides a compound of formula IIIas described above, wherein R²⁰² is 4-hydroxymethylcyclopent-2-ene;2,3-dihydroxy-4-hydroxymethylcyclopent-4-ene;3-hydroxy-4-hydroxymethylcyclopentane;2-hydroxy-4-hydroxymethylcyclopentene;2-fluoro-3-hydroxy-4-hydroxymethylcyclopentane;2,3-dihydroxy-4-hydroxymethyl-5-methylenecyclopentane;4-hydroxymethylcyclopentane, 2,3-dihydroxy-4-hydroxymethylcyclopentane;or 2,3-dihydroxymethylcyclobutane.

In another embodiment the invention provides a compound of formula IIIas described above, wherein R²⁰² is 4-hydroxymethylpyrrolidine;2,3-dihydroxy-4-hydroxymethylpyrrolidine;2/3-hydroxy-4-hydroxymethylpyrrolidine;2-fluoro-3-hydroxy-4-hydroxymethylpyrrolidine; or3-fluoro-2-hydroxy-4-hydroxymethylpyrrolidine.

In another embodiment the invention provides a compound of formula IIIas described above, wherein X is N; Y is NH; R²⁰⁰ is NH₂; R²⁰¹ is H; andR²⁰³ is H; or a pharmaceutically acceptable salt or prodrug thereof.

In another embodiment the invention provides a compound of formula IIIas described above, wherein X is N; Y is NH; R²⁰⁰ is OH; R²⁰¹ is H; andR³ is H; or a pharmaceutically acceptable salt or prodrug thereof.

In another embodiment the invention provides a compound of formula IIIas described above, wherein X is N; Y is S; R²⁰⁰ is NH₂; R²⁰¹ is H; andR²⁰³ is H; or a pharmaceutically acceptable salt or prodrug thereof.

In another embodiment the invention provides a compound of formula IIIas described above, wherein X is N; Y is O; R²⁰⁰ is NH₂; R²⁰¹ is H; andR²⁰³ is H; or a pharmaceutically acceptable salt or prodrug thereof.

In another embodiment the invention provides a compound of formula IIIas described above, wherein X is N; Y is O; R²⁰⁰ is Cl, SH or S-alkyl;R²⁰¹ is H; and R²⁰³ is H; or a pharmaceutically acceptable salt orprodrug thereof.

In another embodiment the invention provides a compound of formula IIIas described above, wherein X is N; Y is O; R²⁰⁰ is Cl; R²⁰¹ is H; andR²⁰³ is H; or a pharmaceutically acceptable salt or prodrug thereof.

In another embodiment the invention provides a compound of formula IIIas described above, wherein X is N; Y is O, S or NH; R²⁰⁰ is OH; R²⁰¹ isNH₂; and R²⁰³ is H; or a pharmaceutically acceptable salt or prodrugthereof.

In another embodiment the invention provides a compound of formula IIIas described above, wherein X is N; Y is O, S or NH; R²⁰⁰ is NHR²⁰⁴,NR²⁰⁴R²⁰⁵, aryl, NR²⁰⁴OR²⁰⁵, NR²⁰⁴NHR²⁰⁵, NHNHR²⁰⁴, SR²⁰⁵ or OR²⁰⁵; R²⁰¹is H, and R²⁰³ is H; or a pharmaceutically acceptable salt or prodrugthereof.

In another embodiment the invention provides a compound of formula IIIas described above, wherein X is CH; Y is O, NH or S; R²⁰⁰ is Cl, aryl,NHR²⁰⁴, NR²⁰⁴R²⁰⁵, OR²⁰⁵, SR²⁰⁵, NHNHR²⁰⁴, NR²⁰⁴NHR²⁰⁵, or NR²⁰⁴OR²⁰⁵;R²⁰¹ is H, and R²⁰³ is H; or a pharmaceutically acceptable salt orprodrug thereof.

In another embodiment the invention provides a compound of formula IIIas described above, wherein X is N; Y is O, S or NH; R²⁰⁰ is NH₂; R²⁰¹is H, R²⁰² is any alkyl group containing hydroxyl; and R²⁰³ is H; or apharmaceutically acceptable salt or prodrug thereof.

In another embodiment the invention provides a compound of formula IIIas described above, wherein: X is N; Y is O or S; R²⁰⁰ is OR²⁰⁵, NHR²⁰⁴,NR²⁰⁴R²⁰⁵, NHNHR²⁰⁴, NR²⁰⁴NHR²⁰⁵, SR²⁰⁵, or Cl; R²⁰¹ is H or NHR²⁰⁴;R²⁰² is a substituted alkyl, moiety from a sugar with the proviso thatwhen Y═NH or S and R²⁰⁰ is NH₂, OH, SH, alkylamino, alkyloxy, oralkylthio, the sugar moiety can not be from ribose or 2-deoxyribose; amoiety from a thio sugar; hydroxyl substituted cycloalkanes; or hydroxylsubstituted 5-pyrrolidine moieties; R²⁰³ is H; R²⁰⁴ is H, or alkyl; andR²⁰⁵ is alkyl; or a pharmaceutically acceptable salt or prodrug thereof.

In another embodiment the invention provides a compound of formula IIIas described above, wherein: X is N; Y is O or S; R²⁰⁰ is OR²⁰⁵, NHR²⁰⁴,NR²⁰⁴R²⁰⁵, NHNHR²⁰⁴, NR²⁰⁴ NHR²⁰⁵, SR²⁰⁵, or Cl; R²⁰¹ is H or NHR²⁰⁴;R²⁰² is a nucleoside sugar group with the proviso that when Y═NH or Sand R²⁰⁰ is NH₂, OH, SH, alkylamino, alkyloxy, or alkylthio, the sugarmoiety is not ribose or 2-deoxyribose; R²⁰³ is H; R²⁰⁴ is H, or alkyl;and R²⁰⁵ is alkyl; or a pharmaceutically acceptable salt or prodrugthereof.

For a compound of formula III, a specific value for X is N.

For a compound of formula III, a specific value for Y is O or S.

For a compound of formula III, a specific value for R²⁰⁰ is OR²⁰⁵,NHR²⁰⁴, NR²⁰⁴R²⁰⁵, NHNHR²⁰⁴, NR²⁰⁴NHR²⁰⁵, SR²⁰⁵, or Cl.

For a compound of formula III, a specific value for R²⁰¹ is H or NHR²⁰⁴.

For a compound of formula III, a specific value for R²⁰² is asubstituted alkyl, moiety from a sugar.

For a compound of formula III, a specific value for R²⁰³ is H, alkyl,aryl, F, Cl, CN, CO₂H or NH₂.

Prodrugs

The term “prodrug” as used herein refers to a compound that can bemetabolized in vivo to provide a compound of formula I, II, or III. Thusprodrugs include compounds that can be prepared by modifying one or morefunctional groups in a compound of formula I, II, or II, to provide acorresponding compound that can be metabolized in vivo to provide acompound of formula I, II, or III. Such modifications are known in theart. For example, one or more hydroxy groups or amine groups in acompound of formula I, II, or III, can be acylated withalkyl-C(═O)-groups or with residues from amino acids to provide aprodrug. Alternatively, one or more pendent hydroxyl groups from amono-, di-, or tri-phosphate functionality in a compound of formula I,II, or III can be converted to an alkoxy, substituted alkoxy, aryloxy,or substituted aryloxy group.

In one embodiment, the term prodrug includes a compound wherein one ormore hydroxy groups on a nucleoside sugar group (e.g. a 2′, 3′, or 5′hydroxy group) have been converted to a group that can be metabolized invivo to provide a compound of formula I, II, or III. For example, theinvention provides a compound wherein one or more hydroxy groups on anucleoside sugar group (e.g. a 2′, 3′, or 5′ hydroxy group) have beenconverted to an acyloxy, acylamino or R—O group, wherein R is acarboxy-linled amino acid.

In one embodiment, the term prodrug includes a compound wherein one ormore pendent hydroxyl groups from a mono-, di-, or tri-phosphatefunctionality in a compound of formula I, II, or III is converted to agroup R_(y)—O—; wherein each R_(y) is independently a 1-20 carbonbranched or unbranched, saturated or unsaturated chain, wherein one ormore (e.g. 1, 2, 3, or 4) of the carbon atoms is optionally replacedwith —O— or —S— and wherein one or more of the carbon atoms isoptionally substituted with oxo (═O) or thioxo (═S) (See Lefebvre etal., J. Med. Chem. 1995, 38, 3941-50).

In another embodiment, the term prodrug includes a compound wherein oneor more pendent hydroxyl groups from a mono-, di-, or tri-phosphatefunctionality in a compound of formula I, II, or III is converted to agroup R_(z)—N—; wherein each R_(z) is a residue of an amino acid. Thus,in the methods of treatment of the present invention, the term“administering” includes administration of a compound of formula I, II,or III, as well as administration of a prodrug which converts to acompound of formula I, II, or III or a salt thereof in vivo.Conventional procedures for the selection and preparation of prodrugderivatives are described, for example, in “Design of Prodrugs”, ed. H.Bundgaard, Elsevier, 1985; and in International Patent ApplicationPublication Number WO 2005/084192. A variety of prodrugs are alsodescribed in International Patent Application Number PCT US2004/013063,which was published as International Publication Number WO 2004/096286.

In another embodiment the prodrug comprises one of more groups offormula:

wherein:

R₁₅ is H, alkyl, substituted alkyl, aryl, substituted aryl, cycloalkyl,substituted cycloalkyl, heteroaryl, substituted heteroaryl,heterocyclic, substituted heterocyclic, and an amino acid;

R₁₆ is H, optionally substituted monocyclic aryl, or optionallysubstituted monocyclic heteroaryl; and R₁₇ is H, halogen, CN, —CO—R₂₀,—CON(R₂₁)₂, —CO₂R₂₀, —SO₂R₂₀, —SO₂N(R₂₁)₂, —OR₂₁, —SR₂₁, —R₂₁, —N(R₂₁)₂,—O—COR₂₀, —O—CO₂R₂₀, —SCOR₂₀, —S—CO₂R₂₀, —NHCOR₂₁, —NHCO₂R₂₁,—(CH₂)_(p)—OR₂₂, or —(CH₂)_(p)—SR₂₂; or R₁₆ and R₁₇ are connected via anadditional 3-5 atoms to form a cyclic group, optionally containing oneheteroatom, that is fused to an aryl group at the beta and gammaposition to the O attached to the phosphorus; or R₁₇ and R₁₈ areconnected as described below;

R₁₈ and R₁₉ are each independently H, alkyl, aryl, heterocycloalkyl,aralkyl, optionally substituted monocyclic aryl or optionallysubstituted monocyclic heteroaryl; or R₁₈ and R₁₉ are connected via anadditional 2-5 atoms to form a cyclic group, optionally containing 0-2heteroatoms; or R₁₇ and R₁₈ are connected via an additional 3-5 atoms toform a cyclic group, optionally containing one heteroatom and R₁₉ is H,alkyl, aryl, heterocycloalkyl, aralkyl, optionally substitutedmonocyclic aryl or optionally substituted monocyclic heteroaryl; and

R₂₀ is alkyl, aryl, heterocycloalkyl, or arylalkyl;

R₂₁ is H, alkyl, aryl, heterocycloalkyl, or arylalkyl;

R₂₂ is H or lower acyl;

n is an integer from 2-5;

m is an integer from 10-20; and

p is an integer from 2-3.

Prodrug forms of a compound bearing various nitrogen functions (amino,hydroxyamino, amide, etc.) may include the following types ofderivatives where each R_(p) group individually may be hydrogen,substituted or unsubstituted alkyl, aryl, alkenyl, alkynyl, heterocycle,alkylaryl, aralkyl, aralkenyl, aralkynyl, cycloalkyl or cycloalkenylgroups as defined earlier.

-   -   (a) Carboxamides, represented as —NHC(O)R_(p)    -   (b) Carbamates, represented as —NHC(O)OR_(p)    -   (c) (Acyloxy)alkyl Carbamates, represented as NHC(O)OROC(O)R_(p)    -   (d) Enamines, represented as —NHCR(═CHCO₂R_(p)) or        —NHCR(═CHCONR_(p)R_(p))    -   (e) Schiff Bases, represented as —N═CR_(p)R_(p)    -   (f) Mannich Bases (from carboximide compounds), represented as        RCONHCH₂NR_(p)R_(p)        Preparations of such prodrug derivatives are discussed in        various literature sources (examples are: Alexander et al., J.        Med. Chem. 1988, 31, 318; Aligas-Martin et al., PCT        WO0041531, p. 30).

Prodrug forms of carboxyl-bearing compounds include esters

(—CO₂R_(m)) where the R_(m) group corresponds to any alcohol whoserelease in the body through enzymatic or hydrolytic processes would beat pharmaceutically acceptable levels. Another prodrug derived from acarboxylic acid form of the disclosure may be a quaternary salt type ofstructure described by Bodor et al., J. Med. Chem. 1980, 23, 469.

Nucleoside Sugar Groups

The term “nucleoside sugar group” as used herein includes cyclic andacyclic groups that can be included as the sugar portion of a nucleosideanalog of formula I, II, or III. Many examples of such groups are knownin the field of nucleoside chemistry (See for example Antiviral Drugs byJohn S. Driscoll (2002) published by Ashgate Publishing Ltd.).

The term nucleoside sugar group includes substituted and unsubstitutedtetrahydrofuranyl and dihydrofuranyl compounds including those set forthin group (A) below, substituted and unsubstituted tetrahydrothiophenyland dihydrothiophenyl compounds including those set forth in group (B)below, substituted and unsubstituted alkyl compounds including those setforth in group (C) below, substituted and unsubstituted cycloalkyl andcycloalkenyl compounds including those set forth in group (D) below,substituted and unsubstituted dihydropyrrolidinyl andtetrahydropyrrolidinyl compounds including those set forth in group (E)below, and substituted and unsubstituted dioxolane, substituted andunsubstituted thioxolane, and substituted and unsubstituted dithiolanecompounds including those set forth in group (F) below.

Group A

Examples of substituted tetrahydro and dihydrofuranyl compounds includethose compounds represented by the general structures:

Specific examples include, but are not limited to, the followingcompounds:

Group B

Examples of substituted tetrahydrothiophenyl and dihydrothiophenylcompounds include those compounds represented by the general structures:

Specific examples include, but are not limited to, the followingcompounds:

Group C

Examples of substituted alkyl compounds include those compoundsrepresented by:

Specific examples include, but are not limited to, the followingcompounds:

Group D

Examples of substituted cycloalkyl and cycloalkenyl compounds includethose compounds represented by the general structures:

Specific examples include, but are not limited to, the followingcompounds:

Group E

Examples of substituted dihydropyrrolidinyl and tetrahydropyrrolidinylcompounds include those compounds represented by the general structures:

Specific examples include, but are not limited to, the followingcompounds:

Group F

Examples of substituted dioxolane, substituted thioxolane andsubstituted dithiolane compounds include those compounds represented bythe general structures:

Specific examples include, but are not limited to, the followingcompounds:

For the structures in Groups A-F, the following definitions apply:

R₇ is H, OR₁₄, N₃, NH₂, or F; and R′₇ is H, F, OH, O-alkyl, alkyl,substituted alkyl, alkenyl, substituted alkenyl, alkynyl, or substitutedalkynyl; or R₇ and R′₇ together may be ═CH₂, ═CHF; wherein both R₇ andR′₇ are not OH; and when one of R₇ and R′₇ is NH₂, the other is not OH;and when one of R₇ and R′₇ is N₃, the other is not OH; R₇″ is alkyl orsubstituted alkyl.

R₈ is H, OR₁₄, N₃, NH₂, or F; and R′₈ is H, F, OH, O alkyl, alkyl,substituted alkyl, alkenyl, substituted alkenyl, alkynyl, or substitutedalkynyl; or R₈ and R′₈ together may be ═CH₂, ═CHF; wherein both R₈ andR′₈ are not OH; and when one of R₈ and R′₈ is NH₂, the other is not OH;and when one of R₈ and R′₈ is N₃, the other is not OH;

R₉ is H, CH₃, C₂H₅, or N₃;

R′₉ is CH₂OR₁₄, CH₂F, CH₂SH, CHFOH, CF₂OH,

R₁₀ and R₁₁ are each independently H, alkyl, aryl, substituted aryl,acyloxyalkyl, or (CH₂)_(n)—O—(CH₂)_(m)CH₃;

R₁₂ is an N-linked amino acid residue (e.g. —NH—CH(CH₃)CO₂alkyl or—NH—CH(isopropyl)-CO₂alkyl);

R₁₃ is H, CH₃, C₂H₅, CH₂F, CH₂OH, CH₂CH₂F, CH₂CH₂OH, CH₂N₃, CH₂CH₂N₃,CH₂NH₂, or CH₂CH₂NH₂; and

R₁₄ is H.

In one embodiment, for a compound of formula I, R₁₄ is replaced to forma pharmaceutically acceptable prodrug, for example, a prodrug selectedfrom the group consisting of: acyl, oxyacyl, phosphonate, phosphate,phosphate esters, phosphonamidate, phosphorodiamidate, phosphoramidatemono ester, cyclic phosphoramidate, cyclic phosphorodiamidate,phosphoramidate diester, C(O) CHR₁₅NH₂,

wherein:

R₁₅ is H, alkyl, substituted alkyl, aryl, substituted aryl, cycloalkyl,substituted cycloalkyl, heteroaryl, substituted heteroaryl,heterocyclic, substituted heterocyclic, or an amino acid;

R₁₆ is H, optionally substituted monocyclic aryl, or optionallysubstituted monocyclic heteroaryl; and R₁₇ is H, halogen, CN, —CO—R₂₀,—CON(R₂₁)₂, —CO₂R₂₀, —SO₂R₂₀, —SO₂N(R₂₁)₂, —OR₂₁, —SR₂₁, —R₂₁, —N(R₂₁)₂,—O—COR₂₀, —O—CO₂R₂₀, —SCOR₂₀, —S—CO₂R₂₀, —NHCOR₂₁, —NHCO₂R₂₁,—(CH₂)_(p)—OR₂₂, or —(CH₂)_(p)—SR₂₂; or R₁₆ and R₁₇ are connected via anadditional 3-5 atoms to form a cyclic group, optionally containing oneheteroatom, that is fused to an aryl group at the beta and gammaposition to the O attached to the phosphorus; or R₁₇ and R₁₈ areconnected as described below;

R₁₈ and R₁₉ are each independently H, alkyl, aryl, heterocycloalkyl,aralkyl, optionally substituted monocyclic aryl or optionallysubstituted monocyclic heteroaryl; or R₁₈ and R₁₉ are connected via anadditional 2-5 atoms to form a cyclic group, optionally containing 0-2heteroatoms; or R₁₇ and R₁₈ are connected via an additional 3-5 atoms toform a cyclic group, optionally containing one heteroatom and R₁₉ is H,alkyl, aryl, heterocycloalkyl, aralkyl, optionally substitutedmonocyclic aryl or optionally substituted monocyclic heteroaryl; and

R₂₀ is alkyl, aryl, heterocycloalkyl, or arylalkyl;

R₂₁ is H, alkyl, aryl, heterocycloalkyl, or arylalkyl;

R₂₂ is H or lower acyl;

n is an integer from 2-5;

m is an integer from 10-20; and

p is an integer from 2-3.

In one embodiment of the invention, R² has the following formula:

wherein:

R³⁰⁰ is alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl,or substituted alkynyl;

R³⁰¹ is H, alkyl, —C(O)alkyl, or aryl-C(═O)—;

R³⁰² is H, OH, —Oalkyl, —OC(O)alkyl, benzoyloxy, —CH₂OH, CH₂NH₂, N₃,CH₂N₃, or NH₂;

R³⁰³ is H, OH, or NH₂; provided both R³⁰² and R³⁰³ cannot be the samegroup except hydrogen;

X is O, S, NH or CH₂;

Z³⁰⁰ is —O—[P(═O)(R³⁰⁷)O—]_(n)—R³⁰⁸, or —CH₂—[P(═O)(R³⁰⁷)O—]_(n)—R³⁰⁸;

each R³⁰⁷ is independently OH, —Oalkyl, or —OC(O)alkyl;

each R³⁰⁸ is independently H, alkyl, or —C(O)alkyl; and

n is 0, 1, 2, or 3.

In one embodiment of the invention, R² has the following formula:

wherein: R³⁰⁰ is H or methyl; R³⁰¹ is H; R³⁰² is OH; R³⁰³ is H; X is O,S, NH or CH₂; Z³⁰⁰ is —O—[P(═O)(R³⁰⁷)O—]_(n)—R³⁰⁸, or—CH₂—[P(═O)(R³⁰⁷)O—]_(n)—R³⁰⁸; each R³⁰⁷ is OH; each R³⁰⁸ is H; and n is0, 1, 2, or 3.

In another embodiment of the invention, R² has the following formula:

wherein: R³⁰⁰ is H or alkyl; R³⁰¹ is H, alkyl, or benzoyl; R³⁰² is OH,or benzoyloxy, R³⁰³ is H; X is O, S, NH or CH₂; Z³⁰⁰ is—O—[P(═O)(R³⁰⁷)O—]_(n)—R³⁰⁸, or —CH₂—[P(═O)(R³⁰⁷)O—]_(n)—R³⁰⁸; each R³⁰⁷is OH; each R³⁰⁸ is H; and n is 0, 1, 2, or 3.

In another embodiment of the invention, R² has the following formula:

wherein: R³⁰⁰ is H or methyl; R³⁰¹ is H, methyl, or benzoyl; R³⁰² is OH,or benzoyloxy, R³⁰³ is H; X is O, S, NH or CH₂; Z³⁰⁰ is—O—[P(═O)(R³⁰⁷)O—]_(n)—R³⁰⁸, or —CH₂—[P(═O)(R³⁰⁷)O—]_(n)—R³⁰⁸; each R³⁰⁷is OH; each R³⁰⁸ is H; and n is 0, 1, 2, or 3.

In another embodiment of the invention, R² has the following formula:

wherein: R³⁰⁰ is H or alkyl; R³⁰³ is H or alkyl; the bond represented by--- is a single or a double bond; X is O, S, NH or CH₂; Z³⁰⁰ is—O—[P(═O)(R³⁰⁷)O—]_(n)—R³⁰⁸, or —CH₂—[P(═O)(R³⁰⁷)O—]_(n)—R³⁰⁸; each R³⁰⁷is OH; each R³⁰⁸ is H; and n is 0, 1, 2, or 3.

In another embodiment of the invention, R² has the formula:—CH₂CH₂OCH₂P(═O)(OH)₂,

Synthetic Processes

Processes for preparing compounds of formula I, II, and III orpharmaceutically acceptable salts or prodrugs thereof, as well asprocesses for preparing intermediate compounds that can be used toprepare compounds of formula I, II, or III or pharmaceuticallyacceptable salts or prodrugs thereof are provided as further embodimentsof the invention. For example in one embodiment the invention provides amethod for preparing a pharmaceutically acceptable salt of compound offormula I, II, or III, comprising converting a corresponding compound offormula I, II, or III to the salt.

In another embodiment the invention provides a method for preparing aprodrug of a compound of formula I, II, or III, comprising converting acorresponding compound of formula I, II, or III to the prodrug.

In another embodiment the invention provides a method for preparing acompound of formula I, II, or III, comprising deprotecting acorresponding compound of formula I, II, or III that comprises one ormore protecting groups to provide the compound of formula I, II, or III.

Synthetic Intermediates

The invention also provides synthetic intermediates that are useful forpreparing compounds of formula I, II, or III. For example, the inventionprovides novel synthetic intermediates such as those described in theExamples herein.

In one embodiment the invention provides a compound of formula:

wherein: R is chloro or bromo; R¹ and Y have any of the values definedherein; and (P)R² is a nucleoside sugar group bearing one or moreprotecting groups.

In one embodiment, the invention provides the compound:2-(3,4-Bis(benzyloxy)-5-(benzyloxymethyl)-tetrahydrofuran-2-yl)acetonitrile;2-(6-((tert-Butyldiphenylsilyloxy)methyl)-2,2,3a-trimethyl-tetrahydrofuro[3,4-d][1,3]dioxol-4-yl)acetonitrile;2-(3,4-Bis(benzyloxy)-5-(benzyloxymethyl)-3-methyl-tetrahydrofuran-2-yl)acetonitrile;2-(3,4-Bis(benzyloxy)-5-(benzyloxymethyl)-3-methyl-tetrahydrofuran-2-yl)acetonitrile;2-(4-(Benzyloxy)-5-(benzyloxymethyl)-3-methoxy-tetrahydrofuran-2-yl)acetonitrile;2-(3-Methyl-5-(trityloxymethyl)-2,5-dihydrofuran-2-yl)acetonitrile;2-(3,4-Bis(benzyloxy)-5-(benzyloxymethyl)-3-ethyl-tetrahydrofuran-2-yl)acetonitrile;Ethyl3-amino-4-(3,4-bis(benzyloxy)-5-(benzyloxymethyl)-tetrahydrofuran-2-yl)furan-2-carboxylate;3-Amino-4-(3,4-bis(benzyloxy)-5-(benzyloxymethyl)-tetrahydrofuran-2-yl)furan-2-carbonitrile;Ethyl3-amino-4-(3,4-bis(benzyloxy)-5-(benzyloxymethyl)-3-methyl-tetrahydrofuran-2-yl)furan-2-carboxylate;3-Amino-4-(3,4-bis(benzyloxy)-5-(benzyloxymethyl)-3-methyl-tetrahydrofuran-2-yl)furan-2-carbonitrile;3-Amino-4-(3,4-bis(benzyloxy)-5-(benzyloxymethyl)-3-vinyl-tetrahydrofuran-2-yl)furan-2-carbonitrile;3-Amino-4-(3,4-bis(benzyloxy)-5-(benzyloxymethyl)-3-ethyl-tetrahydrofuran-2-yl)furan-2-carbonitrile;3-Amino-4-(3,4-bis(benzyloxy)-5-(benzyloxymethyl)-3-(hydroxymethyl)-tetrahydrofuran-2-yl)furan-2-carbonitrile;3-Amino-4-(3-methyl-5-(trityloxymethyl)-2,5-dihydrofuran-2-yl)furan-2-carbonitrile;3-Amino-4-(3,4-bis(benzyloxy)-5-(benzyloxymethyl)-2,5-dihydrofuran-2-yl)thiophene-2-carbonitrile;3-Amino-4-(3,4-bis(benzyloxy)-5-(benzyloxymethyl)-3-methyl-tetrahydrofuran-2-yl)thiophene-2-carbonitrile;3-Amino-4-(4-(benzyloxy)-5-(benzyloxymethyl)-3-methoxy-tetrahydrofuran-2-yl)furan-2-carbonitrile;3-Amino-4-(3,4-bis(benzyloxy)-5-(benzyloxymethyl)-3-methyl-tetrahydrofuran-2-yl)furan-2-carboxamide;3-Amino-4-(3,4-bis(benzyloxy)-5-(benzyloxymethyl)-tetrahydrofuran-2-yl)furan-2-carboxamide;3-Amino-4-(3,4-bis(benzyloxy)-5-(benzyloxymethyl)-3-methyl-tetrahydrofuran-2-yl)furan-2-carbothioamide;3-Amino-4-(3,4-bis(benzyloxy)-5-(benzyloxymethyl)-tetrahydrofuran-2-yl)furan-2-carbothioamide;3-Amino-4-(4-(trityloxymethyl)cyclopent-2-enyl)furan-2-carbonitrile;3-Amino-4-(5-(trityloxymethyl)-tetrahydrothiophen-2-yl)furan-2-carbonitrile;3-Amino-4-(2-(trityloxy)ethyl)furan-2-carbonitrile;2-Amino-7-(3,4-dihydroxy-5-(hydroxymethyl)-tetrahydrofuran-2-yl)furo[3,2-d]pyrimidin-4(3H)-one;or7-(3,4-Dihydroxy-5-(hydroxymethyl)-3-methyl-tetrahydrofuran-2-yl)furo[3,2-d]pyrimidin-4(3H)-one;7-β-(2′,3′,5′-Tri-O-benzyl-D-ribofuranosyl)-furo[3,2-d]pyrimidin-4(3H)-one;4-Chloro-7-β-(2′,3′,5′-tri-O-benzyl-D-ribofuranosyl)-furo[3,2-d]pyrimidine;7-β-(2′,3′,5′-Tri-O-benzyl-2′-C-methyl-D-ribofuranosyl)-furo[3,2-d]pyrimidin-4(3H)-one;4-Chloro-7-β-(2′,3′,5′-tri-O-benzyl-2′-C-methyl-D-ribofuranosyl)-furo[3,2-d]pyrimidine;or 7-(2-(Trityloxy)ethyl)furo[3,2-d]pyrimidin-4-amine.

Isomers and Physical Forms

It will be appreciated by those skilled in the art that compounds of theinvention having a chiral center may exist in and be isolated inoptically active and racemic forms. Some compounds may exhibitpolymorphism. It is to be understood that the present inventionencompasses any racemic, optically-active, polymorphic, tautomeric, orstereoisomeric form, or mixtures thereof, of a compound of the invention(e.g. a compound of formula I, II, or III), which possess the usefulproperties described herein, it being well known in the art how toprepare optically active forms (for example, by resolution of theracemic form by recrystallization techniques, by synthesis fromoptically-active starting materials, by chiral synthesis, or bychromatographic separation using a chiral stationary phase) and how todetermine anti-viral or anti-cancer activity using the standard testsdescribed herein, or using other similar tests which are well known inthe art. Although the invention includes all isomeric forms of thecompounds described herein, one embodiment of the invention providescompounds having the absolute stereochemistry depicted in the Exampleshereinbelow.

For example, it would be known in the field of chemistry that a compoundof formula I:

wherein R is OH would form a tautomer of the following formula:

Accordingly, the invention includes all tautometric forms of thecompounds of formulae I, II, and III.Pharmaceutical Compositions, Modes of Administration and Methods ofTreatment

The present disclosure provides compounds of the general formula (I, II,and III) as detailed above which are inhibitors of DNA and/or RNA viralpolymerases and anticancer agents. Various forms of DNA and RNA viralpolymerases are inhibited by the compounds disclosed, such as but notlimited to viral RdRps. The compounds of the present disclosuretherefore have utility in treating and/or preventing viral infections ina host and in treatment and/or preventing a variety of disease statesand/or conditions caused by or related to such viral infections. In oneembodiment, the compounds are useful in the above mentioned treatingand/or preventing by inhibiting a viral RNA and DNA polymerases. Suchviral agents include, but are not limited to, hepatitis B, hepatitis C,human immunodeficiency virus, Polio, Coxsackie A and B, Rhino, Echo,small pox, Ebola, and West Nile virus. In a particular embodiment, thecausative agent of the viral infection is a flavivirus.

The present disclosure provides for a compound of the general formula(I, II, and III) and a pharmaceutical composition comprising apharmaceutically effective amount of at least one compound of generalformula (I, II, or III) as described herein. Such compounds and/orpharmaceutical compositions may be used in the manufacture of amedicament for treating and/or preventing a disease or condition inwhich it is desirable to inhibit a viral RNA and DNA polymerases. Suchpharmaceutical compositions may also comprise a pharmaceuticallyacceptable carrier and other ingredients known in the art, or maycomprise solely a compound of the general formula (I, II, and III).

The pharmaceutically acceptable carriers described herein, including,but not limited to, vehicles, adjuvants, excipients, or diluents, arewell-known to those who are skilled in the art. Typically, thepharmaceutically acceptable carrier is chemically inert to the activecompounds and has no detrimental side effects or toxicity under theconditions of use. The pharmaceutically acceptable carriers can includepolymers and polymer matrices.

The compounds described in the instant disclosure can be administered byany conventional method available for use in conjunction withpharmaceuticals, either as individual therapeutic agents or incombination with additional therapeutic agents.

The compounds described are administered in a pharmaceutically effectiveamount. The pharmaceutically effective amount of the compound and thedosage of the pharmaceutical composition administered will, of course,vary depending upon known factors, such as the pharmacodynamiccharacteristics of the particular agent and its mode and route ofadministration; the age, health and weight of the recipient; theseverity and stage of the disease state or condition; the kind ofconcurrent treatment; the frequency of treatment; and the effectdesired.

A daily dosage of active ingredient can be expected to be about 0.001 to1000 milligrams (mg) per kilogram (kg) of body weight per day. In oneembodiment, the total amount is between about 0.1 mg/kg and about 100mg/kg of body weight per day; in an alternate embodiment between about1.1 mg/kg and about 50 mg/kg of body weight per day; in yet anotheralternate embodiment between 0.1 mg/kg and about 30 mg/kg of body weightper day. The above described amounts may be administered as a series ofsmaller doses over a period of time if desired. The pharmaceuticallyeffective amount can be calculated based on the weight of the parentcompound to be delivered. If the salt or prodrug exhibits activity initself, the pharmaceutically effective amount can be estimated as aboveusing the weight of the salt or prodrug, or by other means known tothose skilled in the art. The dosage of active ingredient may be givenother than daily if desired.

The total amount of the compound administered will also be determined bythe route, timing and frequency of administration as well as theexistence, nature, and extent of any adverse side effects that mightaccompany the administration of the compound and the desiredphysiological effect. It will be appreciated by one skilled in the artthat various conditions or disease states, in particular chronicconditions or disease states, may require prolonged treatment involvingmultiple administrations.

Dosage forms of the pharmaceutical compositions described herein (formsof the pharmaceutical compositions suitable for administration) containfrom about 0.1 mg to about 3000 mg of active ingredient (i.e. thecompounds disclosed) per unit. In these pharmaceutical compositions, theactive ingredient will ordinarily be present in an amount of about0.5-95% weight based on the total weight of the composition. Multipledosage forms may be administered as part of a single treatment. Theactive ingredient may be administered to achieve peak plasmaconcentrations of the active ingredient of from about 0.2 to 70 μM, orfrom about 1.0 to 10 μM.

The active ingredient can be administered orally in solid dosage forms,such as capsules, tablets, and powders, or in liquid dosage forms, suchas elixirs, syrups and suspensions. It can also be administeredparenterally, in sterile liquid dosage forms. The active ingredient canalso be administered intranasally (nose drops) or by inhalation via thepulmonary system, such as by propellant based metered dose inhalers ordry powders inhalation devices. Other dosage forms are potentiallypossible such as administration transdermally, via patch mechanisms orointment.

Formulations suitable for oral administration can include (a) liquidsolutions, such as a pharmaceutically effective amount of the compounddissolved in diluents, such as water, saline, or orange juice; (b)capsules, sachets, tablets, lozenges, and troches, each containing apredetermined pharmaceutically effective amount of the activeingredient, as solids or granules; (c) powders; (d) suspensions in anappropriate liquid; and (e) suitable emulsions. Liquid formulations mayinclude diluents, such as water and alcohols, for example, ethanol,benzyl alcohol, propylene glycol, glycerin, and the polyethylenealcohols, either with or without the addition of a pharmaceuticallyacceptable surfactant, suspending agent, or emulsifying agent. Capsuleforms can be of the ordinary hard- or soft-shelled gelatin typecontaining, for example, surfactants, lubricants, and inert fillers,such as lactose, sucrose, calcium phosphate, and corn starch. Tabletforms can include one or more of the following: lactose, sucrose,mannitol, corn starch, potato starch, alginic acid, microcrystallinecellulose, acacia, gelatin, guar gum, colloidal silicon dioxide,croscarmellose sodium, talc, magnesium stearate, calcium stearate, zincstearate, stearic acid, and other excipients, colorants, diluents,buffering agents, disintegrating agents, moistening agents,preservatives, flavoring agents, and pharmacologically compatiblecarriers. Lozenge forms can comprise the active ingredient in a flavor,usually sucrose and acacia or tragacanth, as well as pastillescomprising the active ingredient in an inert base, such as gelatin andglycerin, or sucrose and acadia, emulsions, and gels containing, inaddition to the active ingredient, such carriers as are known in theart.

Formulations suitable for parenteral administration include aqueous andnon-aqueous, isotonic sterile injection solutions, which can containanti-oxidants, buffers, bacteriostats, and solutes that render theformulation isotonic with the blood of the patient, and aqueous andnon-aqueous sterile suspensions that can include suspending agents,solubilizers, thickening agents, stabilizers, and preservatives. Thecompound can be administered in a physiologically acceptable diluent ina pharmaceutically acceptable carrier, such as a sterile liquid ormixture of liquids, including water, saline, aqueous dextrose andrelated sugar solutions, an alcohol, such as ethanol, isopropanol, orhexadecyl alcohol, glycols, such as propylene glycol or polyethyleneglycol such as poly(ethyleneglycol) 400, glycerol ketals, such as2,2-dimethyl-1,3-dioxolane-4-methanol, ethers, an oil, a fatty acid, afatty acid ester or glyceride, or an acetylated fatty acid glyceridewith or without the addition of a pharmaceutically acceptablesurfactant, such as a soap or a detergent, suspending agent, such aspectin, carbomers, methylcellulose, hydroxypropylmethylcellulose, orcarboxymethylcellulose, or emulsifying agents and other pharmaceuticaladjuvants.

Oils, which can be used in parenteral formulations, include petroleum,animal, vegetable, or synthetic oils. Specific examples of oils includepeanut, soybean, sesame, cottonseed, corn, olive, petrolatum, andmineral. Suitable fatty acids for use in parenteral formulations includeoleic acid, stearic acid, and isostearic acid. Ethyl oleate andisopropyl myristate are examples of suitable fatty acid esters. Suitablesoaps for use in parenteral formulations include fatty alkali metal,ammonium, and triethanolamine salts, and suitable detergents include (a)cationic detergents such as, for example, dimethyldialkylammoniumhalides, and alkylpyridinium halides, (b) anionic detergents such as,for example, alkyl, aryl, and olefin sulfonates, alkyl, olefin, ether,and monoglyceride sulfates, and sulfosuccinates, (c) nonionic detergentssuch as, for example, fatty amine oxides, fatty acid alkanolamides, andpolyoxyethylene polypropylene copolymers, (d) amphoteric detergents suchas, for example, alkyl .beta.-aminopropionates, and 2-alkylimidazolinequaternary ammonium salts, and (e) mixtures thereof.

The parenteral formulations typically contain from about 0.5% to about25% by weight of the active ingredient in solution. Suitablepreservatives and buffers can be used in such formulations. In order tominimize or eliminate irritation at the site of injection, suchcompositions may contain one or more nonionic surfactants having ahydrophile-lipophile balance (HLB) of from about 12 to about 17. Thequantity of surfactant in such formulations ranges from about 5% toabout 15% by weight. Suitable surfactants include polyethylene sorbitanfatty acid esters, such as sorbitan monooleate and the high molecularweight adducts of ethylene oxide with a hydrophobic base, formed by thecondensation of propylene oxide with propylene glycol.

Pharmaceutically acceptable excipients are also well-known to those whoare skilled in the art. The choice of excipient will be determined inpart by the particular compound, as well as by the particular methodused to administer the composition. Accordingly, there is a wide varietyof suitable formulations of the pharmaceutical composition of thepresent invention. The following methods and excipients are merelyexemplary and are in no way limiting. The pharmaceutically acceptableexcipients preferably do not interfere with the action of the activeingredients and do not cause adverse side-effects. Suitable carriers andexcipients include solvents such as water, alcohol, and propyleneglycol, solid absorbants and diluents, surface active agents, suspendingagent, tableting binders, lubricants, flavors, and coloring agents.

The compounds of the present invention, alone or in combination withother suitable components, can be made into aerosol formulations to beadministered via inhalation. These aerosol formulations can be placedinto pressurized acceptable propellants, such asdichlorodifluoromethane, propane, and nitrogen. Such aerosolformulations may be administered by metered dose inhalers. They also maybe formulated as pharmaceuticals for non-pressured preparations, such asin a nebulizer or an atomizer.

The formulations can be presented in unit-dose or multi-dose sealedcontainers, such as ampules and vials, and can be stored in afreeze-dried (lyophilized) condition requiring only the addition of thesterile liquid excipient, for example, water, for injections,immediately prior to use. Extemporaneous injection solutions andsuspensions can be prepared from sterile powders, granules, and tablets.The requirements for effective pharmaceutically acceptable carriers forinjectable compositions are well known to those of ordinary skill in theart. See Pharmaceutics and Pharmacy Practice, J.B. Lippincott Co.,Philadelphia, Pa., Banker and Chalmers, Eds., 238-250 (1982) and ASHPHandbook on Injectable Drugs, Toissel, 4th ed., 622-630 (1986).

Formulations suitable for topical administration include pastillescomprising the active ingredient in an inert base, such as gelatin andglycerin, or sucrose and acacia, as well as creams, emulsions, and gelscontaining, in addition to the active ingredient, such carriers as areknown in the art. Furthermore, transdermal patches can be prepared usingmethods known in the art.

Additionally, formulations suitable for rectal administration may bepresented as suppositories by mixing with a variety of bases such asemulsifying bases or water-soluble bases. Formulations suitable forvaginal administration may be presented as pessaries, tampons, creams,gels, pastes, foams, or spray formulas containing, in addition to theactive ingredient, such carriers as are known in the art to beappropriate.

One skilled in the art will appreciate that suitable methods ofadministering a compound of the present invention to an patient areavailable, and, although more than one route can be used to administer aparticular compound, a particular route can provide a more immediate andmore effective reaction than another route.

Useful embodiments of pharmaceutical dosage forms for administration ofthe compounds according to the present invention can be illustrated asfollows.

A large number of hard-shell capsules are prepared by filling standardtwo-piece hard gelatine capsules each with 100 mg of powdered activeingredient, 150 mg of lactose, 50 mg of cellulose and 6 mg of magnesiumstearate.

A mixture of active ingredient in a digestible oil such as soybean oil,cottonseed oil or olive oil is prepared and injected by means of apositive displacement pump into molten gelatin to form soft gelatincapsules containing 100 mg of the active ingredient. The capsules arewashed and dried. The active ingredient can be dissolved in a mixture ofpolyethylene glycol, glycerin and sorbitol to prepare a water misciblemedicine mix.

A large number of tablets are prepared by conventional procedures sothat the dosage unit is 100 mg of active ingredient, 0.2 mg of colloidalsilicon dioxide, 5 mg of magnesium stearate, 275 mg of microcrystallinecellulose, 11 mg of starch, and 98.8 mg of lactose. Appropriate aqueousand non-aqueous coatings may be applied to increase palatability,improve elegance and stability or delay absorption.

Immediate release tablets/capsules are solid oral dosage forms made byconventional and novel processes. These units are taken orally withoutwater for immediate dissolution and delivery of the medication. Theactive ingredient is mixed in a liquid containing ingredient such assugar, gelatin, pectin and sweeteners. These liquids are solidified intosolid tablets or caplets by freeze drying and solid state extractiontechniques. The drug compounds may be compressed with viscoelastic andthermoelastic sugars and polymers or effervescent components to produceporous matrices intended for immediate release, without the need ofwater.

Moreover, the compounds of the present invention can be administered inthe form of nose drops, or metered dose and a nasal or buccal inhaler.The drug is delivered from a nasal solution as a fine mist or from apowder as an aerosol.

In one embodiment, the teachings of the present disclosure provide forthe use of such pharmaceutical compositions and medicaments in a methodof treating a viral infection or treating a disease state and/orcondition caused by or related to such viral infection. In oneembodiment, the treatment is the result of the inhibition of a viral RNAor DNA polymerase, such as but not limited to a RdRp. Such treatment orinhibition need not be complete to be useful. The method of treatmentcomprises the steps of: (i) identifying a patient in need of suchtreatment; (ii) providing such pharmaceutical composition containing atleast one compound of the invention; and (iii) administering suchpharmaceutical composition in a therapeutically effective amount totreat the viral infection in a patient in need of such treatment or toinhibit the activity of a viral RNA or DNA polymerase in a patient inneed of such treatment.

In one embodiment, the teachings of the present disclosure provide forthe use of such pharmaceutical compositions and medicaments in a methodof preventing or suppressing a viral infection or preventing orsuppressing a disease state and/or condition caused by or related tosuch viral infection. In one embodiment, the prevention or suppressionis the result of the inhibition of a viral RNA or DNA polymerase, suchas but not limited to a RdRp. Such prevention, suppression or inhibitionneed not be complete to be useful. The method of preventing orsuppressing comprises the steps of: (i) identifying a patient in need ofsuch prevention; (ii) providing such pharmaceutical compositioncontaining at least one compound of the general formula (I, II, or III);and (iii) administering such pharmaceutical composition in atherapeutically effective amount to prevent or suppress the viralinfection in a patient in need of such treatment or to inhibit theactivity of a viral RNA and DNA polymerase in a patient in need of suchtreatment.

The methods of the treating and preventing a viral infection or adisease state and/or condition caused by or related to said viralinfection may further comprise administering a therapeutically effectiveamount of a compound of the present invention in combination with atherapeutically effective amount of another anti-viral agent which, inparticular, may be active against HCV. Agents active against HCVinclude, but are not limited to, ribavirin, levovirin, viramidine,thymosin alpha-1, an inhibitor of HCV NS3 serine protease, an inhibitorof inosine monophosphatedehydrognease, interferon-α, pegylatedinterferon-α (peginterferon-α), a combination of interferon-α andribavirin, a combination of peginterferon-α and ribavirin, a combinationof interferon-α and levovirin, and a combination of peginterferon-α andlevovirin. Interferon-α includes, but is not limited to, recombinantinterferon-α2a, interferon-α2b, a consensus interferon, and a purifiedinterferon-α product.

The compounds and pharmaceutical compositions of the present disclosurecan be administered to patients to prevent and/or treat a number ofcancers. Cancers include, but are not limited to, leukemias andlymphomas such as acute lymphocytic leukemia, acute nonlymphocyticleukemias, chronic lymphocytic leukemia, chronic myelogenous leukemia,Hodgkin's Disease, non-Hodgkin's lymphomas, and multiple myeloma,childhood solid tumors such as brain tumors, neuroblastoma,retinoblastoma, Wilms Tumor, bone tumors, and soft-tissue sarcomas,common solid tumors of adults such as lung cancer, colon and rectumcancer, breast cancer, prostate cancer, urinary cancers, uterinecancers, oral cancers, pancreatic cancer, melanoma and other skincancers, stomach cancer, ovarian cancer, brain tumors, liver cancer,laryngeal cancer, thyroid cancer, esophageal cancer, and testicularcancer. The cancer may be related to a viral infection or an activity ofa viral DNA or RNA polymerase.

The methods of the treating and preventing cancer may also comprisesfurther administering of a chemotherapeutic agent in combination withany of the compounds or pharmaceutical compositions of the presentdisclosure. Any suitable chemotherapeutic agent can be employed for thispurpose. The chemotherapeutic agent is typically selected from the groupconsisting of alkylating agents, antimetabolites, natural products,hormonal agents, and miscellaneous agents.

Examples of alkylating chemotherapeutic agents include carmustine,chlorambucil, cisplatin, lomustine, cyclophosphamide, melphalan,mechlorethamine, procarbazine, thiotepa, uracil mustard,triethylenemelamine, busulfan, pipobroman, streptozocin, ifosfamide,dacarbazine, carboplatin, and hexamethylmelamine.

Examples of chemotherapeutic agents that are antimetabolites includecytosine arabinoside, fluorouracil, gemcitabine, hydroxyurea,mercaptopurine, methotrexate, azaserine, thioguanine, floxuridine,fludarabine, cladribine and L-asparaginase.

Examples of chemotherapeutic agents that are natural products includeactinomycin D, bleomycin, camptothecins, daunomycin, doxorubicin,etoposide, mitomycin C, TAXOL™ (paclitaxel), taxotere, teniposide,vincristine, vinorelbine, mithramycin, idarubicin, MITHRACIN™.(plicamycin), and deoxycoformycin.

An example of a hormonal chemotherapeutic agent includes tamoxifen.Examples of the aforesaid miscellaneous chemotherapeutic agents includemitotane, mitoxantrone, vinblastine, and levamisole.

The ability of a compound to inhibit viral polymerases can be evaluatedusing known assays. The ability of a compound to inhibit HCV NS5Bpolymerase can be evaluated using the following assay.

HCV NS5B Polymerase Assay

Antiviral activity of the test compounds was assessed (Okuse et al.,Antiviral Res. 2005, 65, 23-34) in the stably HCV RNA-replicating cellline, AVA5, derived by transfection of the human hepatoblastoma cellline, Huh7 (Blight et al., Sci. 2000, 290, 1972). Compounds were addedto dividing cultures once daily for three days. Media was changed witheach addition of compound. Cultures generally started the assay at30-50% confluence and reached confluence during the last day oftreatment. Intracellular HCV RNA levels and cytotoxicity were assessed24 hours after the last dose of compound.

Triplicate cultures for HCV RNA levels (on 48-well and 96-well plates)and cytotoxicity (on 96-well plates) were used. A total of six untreatedcontrol cultures, and triplicate cultures treated with α-interferon andribavirin served as positive antiviral and toxicity controls.

Intracellular HCV RNA levels were measured using a conventional blothybridization method in which HCV RNA levels are normalized to thelevels of B-actin RNA in each individual culture (Okuse et al., Antivir.Res. 2005, 65, 23-34). Cytotoxicity was measured using a neutral red dyeuptake assay (Korba and Gerin, Antivir. Res. 1992, 19, 55). HCV RNAlevels in the treated cultures are expressed as a percentage of the meanlevels of RNA detected in untreated cultures.

Representative compounds of formulae I, II, and III demonstratedsignificant activity in this assay.

Compound Synthesis

Compound of formula I, II, and III can be prepared using syntheticintermediates and synthetic procedures that are known, or they can beprepared using the synthetic intermediates and synthetic proceduresidentified in Schemes A1-D2, and the accompanying Examples herein. Thefollowing abbreviations are used herein.

Tr: trityl

Bn: benzyl

TBDPS: tert-butyldiphenylsilyl

m-CPBA: 3-chloroperoxybenzoic acid

TFA: trifluoroacetic acid

TBDMSCl: tert-butyldimethylsilyl chloride

DMF: dimethylformamide

THF: tetrahydrofuran

LDA: lithium diisopropylamine

TEAB: triethylammonium bicarbonate

mMTrCl: monomethoxytrityl chloride

DMAP: dimethylaminopyridine

DEAE: diethylaminoethyl-sepharose

CMA-80: Chloroform 80:MeOH 18:NH₄OH:2

CMA-50: Chloroform 50:MeOH 40:NH₄OH:10

Bz: benzoyl

BnBr: benzyl bromide

LiHMDS: lithium hexamethyldisalazane

TBDPSCl: tert-butyldiphenylsilyl chloride

DMSO: dimethylsulfoxide

RMgBr: alkyl magnesium bromide

DIBAL: diisobutylaluminum hydride

DBN: 1,5-diazabicyclo[4.3.0]non-5-ene

DBU: 1,8-diazabicyclo[5.4.0]undec-7-ene

MeMgBr: methylmagnesium bromide

Preparation of R²—CH₂CN Compounds:

Preparation of Compounds of the Invention from R²CH₂CN Intermediates

In the following schemes, R² is a nucleoside sugar group (e.g. asubstituted tetrahydro or dihydrofuranyl; a substituted tetrahydro ordihydrothiophenyl; a substituted alkyl, substituted cycloalkyl orcycloalkenyl; a substituted pyrrolidinyl; or a substituted dioxolanyl,thioxolanyl or dithiolanyl). (P)R² is a nucleoside sugar group bearingone or more protecting groups.

Deprotection of protecting groups in R₂ gives the target moleculesNR₄R₅=Azetidine, pyrrolidineR₄, R₅═H, CH₃, C₂H₅, n-C₃H₇, i-C₃H₇,

CH₂CH₂OH, CH₂CH₂NH₂, NH₂(CH₂)_(n)NH₂

Preparation of Monophosphates and Triphosphates of Nucleosides(Represented by Examples C-1 to C-6)

The following Schemes illustrate the preparation of compounds of formulaI, II, and III that have one or more phosphate groups. In these Schemes,B represents the furopyrimidine or thienopyrimidine base of formula I,and B(P) represents the furopyrimidine or thienopyrimidine base offormula I, bearing one or more protecting groups.

Preparation of Prodrugs

The following Schemes illustrate the preparation of prodrugs of theinvention.

The invention will now be illustrated by the following non-limitingExamples.

EXAMPLES Example A-1

4-(Trityloxy)butanenitrile (Scheme A-1)

To a solution of 3-cyano-1-n-propanol (16.85 g, 198 mmol, prepared bymethod of Blicke, et al., J. Org. Chem. 1961, 26, 3685) indichloromethane (250 mL) were added triethylamine (80.1 g, 792 mmol) andtrityl chloride (82.8 g, 297 mmol) at room temperature and the mixturewas stirred for 16 h. To the reaction mixture was added methanol (25 mL)and stirred for 1 h. After concentration, the residue was purified on acolumn of silica gel using ethyl acetate and hexanes as eluent to give40 g (61.7%) of the desired product.

¹HNMR (DMSO-d₆): δ 7.15-7.40 (m, 15H), 3.01-3.12 (m, 2H), 2.51-2.64 (m,2H), 1.75-1.90 (m, 2H).

Example A-2

2-(3,4-Bis(benzyloxy)-5-(benzyloxymethyl)-tetrahydrofuran-2-yl)acetonitrile(Scheme A-1)

Step 1: To a solution of D-ribose (61 g, 406.66 mmol) in methanol (1 L)was added conc. sulfuric acid (6.1 mL) and stirred at 4° C. for 16 h.The reaction mixture was neutralized using triethylamine (40 mL),concentrated to dryness and co-distilled twice with 200 mL of toluene toremove trace amount of water. This furnished 72 g of crudeO-methyl-D-ribofuranose, which was used as such for next step.

Step 2: To a slurry of NaH (65 g, 60%, 1.626 mol) in DMF (200 mL) wasadded crude compound from Step 1 (72 g, 406.66 mmol) in DMF (800 mL)over a period of 0.5 h, maintaining the temperature below 5° C. Theanion formed was stirred at room temperature for 30 min. Benzyl bromide(219.1 g, 1280.9 mmol) was added dropwise over a period of 1 hmaintaining temperature between 0-5° C. The reaction was stirred at roomtemperature for 12 h (TLC analysis in 30% ethyl acetate/hexane showedcomplete disappearance of starting material), was diluted with water(500 mL) and extracted with ethyl acetate (2×1 L). The combined organicextracts were washed twice with water (1 L), brine (500 mL), and driedover MgSO₄ and filtered. The filtrate was concentrated under vacuum tofurnish crude residue. The crude residue was purified by flashchromatography (silica gel 1 kg), eluting with ethyl acetate in hexanesto furnish 112 g (63.3%) of desired product as an oil.

¹H NMR (DMSO-d₆): δ 7.36-7.27 (m, 15H), 4.92 (s, 1H), 4.66-4.44 (m, 6H),4.12-4.07 (m, 1H), 3.97 (dd, J=6.78 and 4.5 Hz, 1H), 3.91 (d, J=4.5 Hz,1H), 3.55 (dd, J=10.73 and 3.4 Hz, 1H), 3.42 (dd, J=10.7 and 6.0 Hz,1H), 3.21 (s, 3H).

Step 3: To a solution of product from Step 2 (114 g, 262.35 mmol) indioxane (250 mL) was added 4 N HCl (250 mL) and heated at reflux for 4h. The reaction mixture was allowed to attain room temperature anddiluted with ethyl acetate (1.5 L). The aqueous layer was separated andextracted with ethyl acetate (3×1 L). The organic layers were combined,washed with water (2×500 mL), saturated aqueous NaHCO₃ (250 mL), water(500 mL), and brine (250 mL), and dried over MgSO₄ and filtered. Thefiltrate was concentrated under vacuum to furnish crude product. Thecrude product was purified by flash chromatography (silica gel 1.5 kg,eluting with ethyl acetate in hexanes 0 to 30%) to furnish startingmaterial (9.9 g,) and 85.3 g (45%) of desired product (mixture ofisomers) as an oil.

¹H NMR (DMSO-d₆): δ 7.32-7.25 (m, 15H), 6.57 (d, J=4.8 Hz, 0.7H, D₂Oexchangeable), 5.82 (d, J=7.7 Hz, 0.3H), 5.26 (dd, J=7.7, 3.5 Hz, 0.3H),5.21 (dd, J=4.8, 1.3 Hz, 0.7H), 4.70-4.43 (m, 6H), 4.16 (q, J=4.1 Hz,0.3H), 4.06-3.96 (m, 1.3H), 3.93-3.87 (m, 0.7H), 3.80 (dd, J=4.3, 1.5Hz, 0.7H), 3.58-3.41 (m, 2H);

Step 4: To a stirred solution of product from Step 3 (15 g, 35.67 mmol)in THF (150 mL) was added diethyl (cyanomethyl)phosphonate (6.95 g,39.23 mmol) at room temperature followed by lithiumbis(trimethylsilyl)amide (39.2 mL, 1M solution in THF) addition at −78°C. The reaction mixture was stirred at −78° C. for about 20 min and at0° C. for 1.5 h and then was quenched by adding water (50 mL). Thereaction was extracted with ether (2×200 mL), washed with water (2×50mL), brine (1×50 mL), and dried over MgSO₄. After filtration, thefiltrate was concentrated and purified by flash chromatography using 0to 30% ethyl acetate in hexanes to give 10.79 g (68.2%) of desiredcompound as a mixture of isomers as an oil.

MS (ES⁺) 444.33 (M+1).

Example A-3

2-(6-((tert-Butyldiphenylsilyloxy)methyl)-2,2,3a-trimethyl-tetrahydrofuro[3,4-d][1,3]dioxol-4-yl)acetonitrile(Scheme A-2)

Step 1: A solution of 2′-C-methyl-1,3,5-tribenzoylribofuranose (19.1 g,40.09 mmol, prepared according to literature procedures (a) Harry-O'kuruet. al., J. Org. Chem. 1997, 62, 1754-1759 and (b) Du, J. et. al.Nucleosides &Nucleotides, 1999, 18, 187-195) in MeOH (850 mL) wastreated with NaOMe (25 wt % in MeOH, 55 mL, 240.35 mmol) followed bystirring at room temperature for 2.5 h. The reaction mixture wasneutralized with conc. HCl until pH reached between 7 and 8 andconcentrated to dryness. The residue was treated with MeOH (300 mL),stirred, filtrated to remove insolubles, and the filtrate wasconcentrated. The residue was treated with water (400 mL) and extractedwith EtOAc (2×200 mL). The aqueous phase was concentrated to dryness togive 11.64 g of yellow syrup. Part of the syrup (474 mg) was treatedwith DMF (6 mL), imidazole (325 mg, 4.77 mmol), and TBDPSCl (0.50 mL,1.92 mmol) followed by stirring at room temperature for 22 h. Thereaction mixture was diluted with EtOAc (100 mL) and washed with water(2×50 mL), brine (50 mL), and dried over MgSO₄. After filtration, thefiltrate was concentrated and the residue was purified on a silica gelcolumn using hexanes:ethyl acetate (1:0 to 1:1) as eluent to give 293 mg(45%, two steps) of product as a colorless oil.

¹H NMR (a mixture of anomeric isomers, ratio=1:3, CDCl₃): δ 7.70-7.62(m, 4H), 7.45-7.34 (m, 6H), 5.07, 5.03 (s, s, 1H), 4.15-3.69 (m, 4H),1.36, 1.31 (s, s, 3H), 1.07, 1.05 (s, s, 9H). MS (ES⁺) 425.41 (M+Na).

Step 2: A mixture of compound from Step 1 (7.2 g, 17.89 mmol),dimethoxypropane (27 mL, 98%, 0.22 mol), p-TsOH (160 mg, 0.84 mmol) inacetone (80 mL) was stirred at room temperature for 1 h. The reactionmixture was treated with EtOAc (800 mL), water (500 mL), saturatedNaHCO₃ (30 mL), and the organic layer was separated. The aqueous phasewas further extracted with EtOAc (500 mL). The combined organic extractswere washed with water (2×300 mL), brine (300 mL), and dried over MgSO₄.After filtration, the filtrate was concentrated and the residue waspurified on a silica gel column using hexanes:ethyl acetate (1:0 to10:1) as eluent to give 6.16 g (58%) of desired product with someinseparable undesired compound as a colorless oil which was used as suchfor the next step.

Step 3: A suspension of NaH (60%, 760 mg, 19 mmol) in DME (65 mL) wascooled to 0° C. and treated with diethyl cyanomethylphoshonate (3.1 mL,19 mmol) dropwise. After stirring for 10 min at about 0° C., the mixturewas treated dropwise with a solution of product from Step 2 (4.2 g, 9.49mmol) in DMF (25 mL) followed by stirring at room temperature for 2 h.The reaction mixture was treated with ether (500 mL) and water (250 mL)and organic layer was separated. The aqueous phase was further extractedwith ether (250 mL) and the combined organic extracts were washed withwater (2×250 mL), and dried over MgSO₄. After filtration, the filtratewas concentrated and the residue was purified on a silica gel columnusing hexanes:ethyl acetate (1:0 to 10:1) as eluent to give 2.84 g (50%,two steps) of2-(6-((tert-butyldiphenylsilyloxy)methyl)-2,2,3a-trimethyl-tetrahydrofuro[3,4-d][1,3]dioxol-4-yl)acetonitrileas a colorless oil.

¹H NMR (CDCl₃): δ 7.76-7.60 (m, 4H), 7.59-7.49 (m, 6H), 4.59 (bs, 1H),4.15-4.03 (m, 2H), 3.84-3.73 (m, 2H), 2.93 (dd, J=16.8, 4.5 Hz, 1H),2.70 (dd, J=16.7, 8.1 Hz, 1H), 1.46 (s, 3H), 1.44 (s, 3H), 1.42 (s, 3H),1.08 (s, 9H). MS (ES⁺) 488.35 (M+Na).

Example A-4

2-(3-(Benzyloxy)-4-(2,4-dichlorobenzyloxy)-5-((2,4-dichlorobenzyloxy)methyl)-3-methyl-tetrahydrofuran-2-yl)acetonitrile(Scheme A-3)

Step 1: A solution of3,5-bis-O-(2,4-dichlorophenylmethyl)-2-C-β-methyl-1-O-methyl-α-D-ribofuranose(20.11 g, 40.53 mmol, prepared according to literature procedures a)Martin, P., Helvetica Chimica Acta, 1995, 78, 486-504 and b) Eldrup etal., J. Med. Chem. 2004, 47, 5284-5297) in THF (500 mL) was treated withNaH (60%, 6.45 g, 161.25 mmol) and stirred at room temperature for 0.5 hfollowed by addition of BnBr (14.6 mL, 122.74 mmol) over 10 min. Thereaction mixture was stirred at 70° C. overnight and diluted with EtOAc(2 L), washed with water (2×) and brine, and dried over MgSO₄. Afterfiltration, the filtrate was concentrated and the residue was purifiedon a silica gel column using hexanes:ethyl acetate (1:0 to 4:1) aseluent to give 16.2 g (68%) of desired product as a yellow oil.

¹H NMR (DMSO-d₆): δ 7.70-7.25 (m, 11H), 4.85-4.50 (m, 7H), 4.20-4.13 (m,1H), 3.76-3.67 (m, 3H), 3.37 (s, 3H), 1.40 (s, 3H); IR (neat, cm⁻¹)2904, 1591, 1472, 1199, 1102; Anal. Calcd for C₂₈H₂₈Cl₄O₅: C, 57.36; H,4.81; Cl, 24.19. Found: C, 57.23; H, 4.65; Cl, 24.32; MS (ES⁺) 609.07(M+Na).

Step 2: A mixture of product from Step 1 (15.19 g, 25.91 mmol) and 3MH₂SO₄/HOAc (1:4, 150 mL) was heated at 70° C. for 9 h. The reactionmixture was diluted with chloroform (500 mL) and washed with water (2×),1M NaHCO₃, water, and dried over MgSO₄. After filtration, the filtratewas concentrated and the residue was purified on a silica gel columnusing hexanes:ethyl acetate (1:0 to 4:1) as eluent to give 8.6 g (58%)of desired product as a light yellow oil.

¹H NMR (a mixture of anomeric isomers, ratio=5:4, DMSO-d₆): δ 7.80-7.40(m, 11H), 6.86 and 6.23 (2d, J=4.8 and 6.3 Hz, 1H), 6.23 (J=6.3 Hz) (2d,1H), 5.25-5.19 (m, 1H), 4.95-4.70 (m, 6H), 4.42-3.75 (m, 4H), 1.55, 1.53(2s, 3H); IR (neat, cm⁻¹) 3435, 2916, 2873, 1591, 1472, 1384, 1095; MS(ES⁺) 593.03 (M+Na); Anal. Calcd for C₂₇H₂₆Cl₄O₅: C, 56.66; H, 4.58; Cl,24.78. Found: C, 56.44; H, 4.48; Cl, 24.76.

Step 3. A solution of product from Step 2 (4.25 g, 7.43 mmol) in THF (35mL) was cooled to −78° C. and treated with diethyl cyanomethylphoshonate(3.6 mL, 22.25 mmol) followed by addition of 1M lithiumbis(trimethylsilyl)amide (9 mL). The reaction mixture was warmed to roomtemperature and stirred for 21 h. It was diluted with ether (400 mL) andwater (200 mL) and the organic layer was separated. The aqueous phasewas further extracted with ether (200 mL). The combined organic extractswere washed with water (2×) and dried over MgSO₄. After filtration, thefiltrate was concentrated and the residue was purified on a silica gelcolumn using hexanes:ethyl acetate (1:0 to 4:1) as eluent to give 3.9 g(88%) of desired product as a colorless oil.

¹H NMR (a mixture of anomeric isomers, ratio=3:2, DMSO-d₆): δ 7.53-7.10(m, 11H), 4.71-4.43 (m, 7H), 4.07-3.75 (m, 2H), 3.62-3.48 (m, 2H),2.77-2.54 (m, 2H), 1.35, 1.21 (2s, 3H); IR (neat, cm⁻¹) 2879, 2252,1591, 1472, 1383, 1095; MS (ES⁺) 618.13 (M+Na) Anal. Calcd forC₂₉H₂₇C4NO₄: C, 58.51; H, 4.57; N, 2.35. Found: C, 58.31; H, 4.49; N,2.27.

Example A-5

2-(3,4-Bis(benzyloxy)-5-(benzyloxymethyl)-3-methyl-tetrahydrofuran-2-yl)acetonitrile(Scheme A-4)

Step 1: To a solution of the compound from Step 2 of Example A-2 (111 g,255.45 mmol) in CH₂Cl₂ (800 mL) at −20° C. was added dropwise a solutionof stannic chloride (280.99 mL, 1M solution in CH₂Cl₂, 280.99 mmol) overa period of 30 min while stirring and maintaining the temperaturebetween −20 and −10° C. After the solution was kept at 0° C. for 23 h,the reaction mixture was quenched carefully by the addition of saturatedNaHCO₃ solution (1 L) over a 10-min period. Tin salts were removed viafiltration through Celite®, and from the filtrate the organic phase wasseparated. The aqueous layer was extracted with chloroform (1000 mL).The combined organic extracts were washed twice with water (500 mL) andbrine (200 mL), and dried over MgSO₄. After filtration, the filtrate wasconcentrated to furnish crude product as dark yellow oil. The crude oilwas purified by flash chromatography (silica gel 1 kg, eluting withethyl acetate in hexanes) to furnish 78.7 g (89.5%) of4-(benzyloxy)-5-(benzyloxymethyl)-2-methoxy-tetrahydrofuran-3-ol as anoil.

¹H NMR (DMSO-d₆): δ 7.35-7.26 (m, 10H), 4.77 (d, J-=4.3 Hz, 1H), 4.56(dd, J=42.8 and 12.4 Hz, 2H), 4.46 (bs, 2H), 4.06 (dd, J=8.3 and 4.3 Hz,1H), 3.98 (dd, J=6.6 and 4.7 Hz, 1H), 3.68 (dd, J=6.6 and 3.8 Hz, 1H),3.44 (d, J=4.5 Hz, 2H), 3.30 (bs, 3H); IR (neat) 3554.8, 3030.7, 2926.0,2912.0, 2863.2, 1957.1, 1732.1, 1650.4, 1494.8, 1452.4, 1414.7, 1362.0,1323.2, 1269.2, 1187.7, 1124.5, 1095.7, 1040.0, 914.4, 853.3, 738.8 and698.5 cm⁻¹; MS (ES⁺) 367.38 (M+Na); Anal. Calcd for C₂₀H₂₄O₅: C, 69.74;H, 7.02. Found: C, 69.84; H, 7.00.

Step 2: A solution of DMSO (45.05 g, 576.66 mmol) in anhydrous CH₂Cl₂(150 mL) was added dropwise to a solution of oxalylchloride (36.88 g,290.5 mmol) at −78° C. with stirring over a period of 30 min(maintaining the internal temperature below −65° C. during addition). Tothis was added dropwise a solution of compound from Step 1 in CH₂Cl₂(150 mL) over a period of 30 min. The reaction mixture was stirred at−70° C. for 3.5 h and quenched by dropwise addition of triethylamine(113.08 g, 1117.5 mmol) at −70° C. over 30 min. The reaction mixture wasallowed to warm to room temperature and diluted with water (500 mL). Theorganic layer was separated and aqueous layer was extracted withchloroform (2×500 mL). The combined organic layers were washed withwater (1 L), brine (1 L), and dried over MgSO₄. After filtration, thefiltrate was concentrated and the residue was dried under vacuum tofurnish 79 g of the product as a light yellow syrup. This compound wasused as such without further purification for the next step.

Step 3: A solution of MeMgBr (3M in ether, 263.5 mL, 790.5 mmol) wasadded dropwise to a solution of compound from Step 2 (76.4 g, 223.5mmol) in anhydrous diethyl ether at −70° C. over a period of 2 h(maintaining the inside temperature around −70° C.). The reaction wasstirred at the same temperature for 2.5 h (TLC analysis using 30% ethylacetate in hexanes of an aliquot showed completion of reaction). Thereaction mixture was quenched by pouring into ice cold water (3 L) andneutralized with 1N HCl (750 mL) to pH 6-7. The aqueous layer wasseparated and extracted once with ethyl acetate (2 L). The combinedorganic layers were washed with water (2×1 L), saturated NaHCO₃ (2×200mL) and brine (250 mL), and dried over MgSO₄. After filtration, thefiltrate was concentrated and the residue was purified on a silica gelcolumn (1 kg silica gel) and eluted with ethyl acetate in hexanes (0 to25%) to furnish 41 g (50%) of desired product which was used in the nextreaction without further purification.

Step 4: To a solution of compound from Step 3 (40 g, 111.6 mmol) in DMF(250 mL) at 0° C. was added 60% NaH (17.85 g, 446.4 mmol) and themixture was stirred at 20° C. for 30 min. To this mixture at 0° C. wasadded benzyl bromide (23.86 g, 139.5 mmol) dropwise over a period of 30min and was heated at 70° C. for 19 h. After cooling to roomtemperature, the reaction mixture was diluted with water (100 mL) andacidified with acetic acid to pH 7-8. The reaction mixture was extractedwith ethyl acetate (2×500 mL) and the combined organic layers werewashed with water (1 L), brine (1 L), and dried over MgSO₄ (200 g).After filtration, the filtrate was concentrated and the residue waspurified by flash chromatography (1 kg silica gel, eluting with ethylacetate in hexanes 0 to 20%) to furnish 33.78 g (67.4%) of desiredproduct as an oil.

¹H NMR (DMSO-d₆): δ 7.39-7.23 (m, 15H), 4.72 (s, 1H), 4.64 (dd, J=15.4and 11.6 Hz, 2H), 4.55-4.44 (m, 4H), 4.06 (dd, J=9.4 and 4.9 Hz, 1H),3.61-3.51 (m, 3H), 3.30 (s, 3H), 1.32 (s, 3H); IR (neat) 3427, 3063,3030, 2901, 1952, 1495, 1453, 1369, 1200, 1103, 1028, 736 and 698 cm⁻¹;MS (ES⁺) 471.38 (M+Na). Anal. Calcd for C₂₈H₃₂O₅: C, 74.97; H, 7.19.Found: C, 74.87; H, 7.22.

Step 5: To a solution of product from Step 4 (33.5 g, 74.77 mmol) indioxane (250 mL) was added 2 N HCl (250 mL) and heated at reflux for 20h. The reaction mixture was allowed to attain room temperature anddiluted with ethyl acetate (1 L) and organic layer was collected. Theaqueous layer was further extracted with ethyl acetate (1 L). Thecombined organic layers were washed with water (2×500 mL), saturatedaqueous NaHCO₃ (150 mL), and brine (500 mL), and dried over MgSO₄. Afterfiltration, the filtrate was concentrated and the residue was purifiedby flash chromatography (1.5 kg silica gel, eluting with ethyl acetatein hexanes) to furnish 14.52 g (45%) of desired product,3,4-bis(benzyloxy)-5-(benzyloxymethyl)-3-methyl-tetrahydrofuran-2-ol, asan oil which is a mixture of isomers.

¹H NMR (DMSO-d₆): δ 7.38-7.24 (m, 15H), 6.60 (bs, 1H, D₂O exchangeable),5.00 (s, 0.7H), 4.99 (s, 0.3H), 4.73-4.47 (m, 6H), 4.19-4.14 (m, 0.3H),4.06-4.00 (m, 0.7H), 3.79 (d, J=7.5 Hz, 0.7H), 3.67 (d, J=6.2 Hz, 0.3H),3.61-3.49 (m, 2H), 1.34 (s, 2H), 1.32 (s, 1H);); IR (neat): 3425, 3064,3031, 2926, 2870, 1954, 1878, 1812, 1735, 1603, 1497, 1454, 1364, 1311,1252, 1202, 1094, 1028, 910, 855, 814, 737, 698 cm⁻¹; MS (ES⁺) 457.38(100% M+Na).

Step 6: To a stirred solution of compound from Step 5 (14.06 g, 32.37mmol) in THF (150 mL) was added diethyl (cyanomethyl)phosphonate (6.30g, 35.60 mmol) and cooled to −78° C. To this cooled solution, lithiumbis(trimethylsilyl)amide (35.60 mL, 35.60 mmol, 1M solution in THF) wasadded over a period of 15 min. The temperature of the reaction mixturewas brought to 20° C. over a period of 4 h and further stirred foranother 16 h. The reaction mixture was again cooled to −78° C. and tothis were added diethyl (cyanomethyl)-phosphonate (8.6 g, 48.55 mmol)and lithium bis(trimethylsilyl)amide (16.18 mL, 16.18 mmol, 1M solutionin THF) and stirred for 24 h at 20° C. The reaction was quenched byadding water (50 mL), stirred for 30 min and extracted with ethylacetate (2×1000 mL). The combined organic extracts were washed withwater (1×500 mL), brine (1×250 mL), and dried (MgSO₄). After filtration,the filtrate was concentrated to afford 14.7 g (98.6%) of the product,which was used as such for next step.

Example A-6

2-(4-(Benzyloxy)-5-(benzyloxymethyl)-3-methoxy-tetrahydrofuran-2-yl)acetonitrile(Scheme A-5)

Step 1: A solution of compound from Example A-5, Step 1 (4 g, 11.61mmol) in DMF (95 mL) was treated with NaH (60%, 1.86 g, 46.5 mmol) andstirred at room temperature for 1 h followed by addition of MeI (0.87mL, 13.84 mmol) in DMF (15 mL). The reaction mixture was stirred at roomtemperature for 23 h and was diluted with EtOAc (600 mL), neutralizedwith HOAc, washed with water (2×300 mL) and brine (200 mL), and driedover MgSO₄. After filtration and concentration of the filtrate, theresidue (5.8 g, light yellow oil) was used as such for next step.

MS (ES⁺) 381.46 (M+Na).

Step 2: A solution of product from Step 1 (5.8 g crude) in a mixture of3M H₂SO₄/HOAc (1:4, 60 mL) was heated at 70° C. for 2 h. The reactionmixture was diluted with chloroform (300 mL) and washed with water(2×200 mL), 1M NaHCO₃ (200 mL), water again (200 mL), and dried overMgSO₄. After filtration and concentration of the filtrate, the residue(4.5 g, yellow oil) was used as such for next step.

MS (ES⁺) 367.48 (M+Na).

Step 3: A solution of product from Step 2 (3.5 g) in THF (42 mL) wascooled to −78° C. and treated with diethyl (cyanomethyl)phosphonate (4.2mL, 25.96 mmol) followed by addition of 1M lithiumbis(trimethylsilyl)amide in THF (10.5 mL, 10.5 mmol). The reactionmixture was warmed to room temperature and stirred for 18 h and wasdiluted with ether (400 mL) and water (200 mL). The aqueous phase wasextracted further with ether (200 mL). The combined organic extractswere washed with water (2×200 mL) and dried over MgSO₄. After filtrationand concentration of the filtrate, the residue was purified on a silicagel column using hexanes:ethyl acetate (1:0 to 2:1) as eluent to give2.4 g (a mixture of anomeric isomers, 72% for three steps) of2-(4-(benzyloxy)-5-(benzyloxymethyl)-3-methoxy-tetrahydrofuran-2-yl)acetonitrileas a colorless oil.

MS (ES⁺): 390.43 (M+Na)⁺.

Example A-7

2-(3-Methyl-5-(trityloxymethyl)-2,5-dihydrofuran-2-yl)acetonitrile(Scheme A-6)

Step 1: To a solution of 3-methyl-5-trityloxymethyl-5H-furan-2-one (1.85g, 5 mmol, prepared by the method of Lopez-Herrera et. al., J.Carbohydrate Chem. 1994, 13, 767) in toluene (25 mL) under N₂ atmosphereat −78° C. was added dropwise with stirring DiBAL (10 mL, 10 mmol, 1Msolution in toluene). The addition rate was maintained to keep thetemperature of the reaction below −70° C. The reaction was stirred at−78° C. for 2 h and quenched with ethyl acetate (4 mL) at thattemperature. The reaction mixture was allowed to warm to roomtemperature and concentrated under vacuum to dryness. The residueobtained was purified by flash chromatography on silica gel eluting with20% ethyl acetate in hexanes to furnish 1.65 g (88%) of3-methyl-5-trityloxymethyl-2,5-dihydrofuran-2-ol (a mixture of isomers)as a white solid; mp 100-102° C.

¹H NMR (DMSO-d₆): δ 7.43-7.23 (m, 15H), 6.31 (dd, J=2.8 and 7.3 Hz, 1H),5.74-5.65 (m, 2H), 4.85 (bs, 0.4H), 4.65 (bs, 0.6H), 3.06 (dd, J=6.8 and9.1 Hz, 0.6H), 2.95-2.83 (m, 1.4H), 1.69, 1.66 (2s, 3H); IR (KBr) 3414,3058, 3028, 2918, 2869, 1962, 1737, 1597, 1489, 1445, 1222, 1069, 1033,985, 747, 702 cm⁻¹; Anal. Calcd for C₂₅H₂₄O₃: C, 80.61; H, 6.50. Found:C, 80.15; H, 6.39.

Step 2: To a slurry of NaH (0.19 g, 4.8 mmol, 60%) in DME (24 mL) cooledto 0° C. was added dropwise diethyl (cyanomethyl)phosphonate (0.96 mL, 6mmol). The solution became homogenous on completion of addition and wasstirred at 0° C. for 30 min. To this solution was added dropwise asolution of product from Step 6,3-methyl-5-trityloxymethyl-2,5-dihydro-furan-2-ol (1.85 g, 5 mmol) inDME (15 mL). The reaction mixture was allowed to warm to roomtemperature, stirred overnight, diluted with water (50 mL) and wasextracted with ether (2×50 mL). The combined organic layers were washedwith water (50 mL), brine (50 mL), and dried over MgSO₄. Afterfiltration, the filtrate was concentrated and the residue was purifiedby flash chromatography (25 g silica gel) eluting with ethyl acetate inhexanes to furnish 1.06 g (90%) of2-(3-methyl-5-trityloxymethyl-2,5-dihydro-furan-2-yl)-acetonitrile (amixture of isomers), as a colorless oil.

¹H NMR (CDCl₃): δ 7.47-7.41 (m, 6H), 7.33-7.19 (m., 9H), 5.64 (s, 0.6H),5.53 (s, 0.4H), 5.10 (m, 0.4H), 4.96-4.83 (m, 1.6H), 3.26 (dd, J=5.6 and9.7 Hz, 0.4H), 3.18-3.05 (m, 1.6H), 2.83-2.53 (m, 2H), 1.79 (m, 3H); IR(KBr) 3430, 3059, 2917, 2865, 2363, 2249, 1967, 1735, 1491, 1445, 1242,1074, 993, 748, 704 cm⁻¹; Anal. Calcd for C₂₇H₂₅NO₂: C, 81.07; H, 6.43;N, 3.50. Found: C, 81.37; H, 6.25; N, 3.49.

Example A-8

2-(3,4-Bis(benzyloxy)-5-(benzyloxymethyl)-3-ethyl-tetrahydrofuran-2-yl)acetonitrile(Scheme A-4)

Step 1: A solution of oxalylchloride (4 mL, 0.04 mol) was added dropwiseto a solution of DMSO (6.18 mL, 0.087 mol) in anhydrous CH₂Cl₂ (100 mL)at −78° C. with stirring over a period of 30 min. To this was addeddropwise a solution of product from Step 1 of Example A-5 (10 g, 0.029mol) in CH₂Cl₂ (25 mL) over a period of 30 min. The reaction mixture wasstirred at −70° C. for 3.5 h and quenched by dropwise addition oftriethylamine (5 mL) at −70° C. over 30 min. The reaction mixture wasallowed to warm to room temperature and diluted with water (200 mL). Theorganic layer was separated and aqueous layer was extracted withchloroform (2×200 mL). The combined organic layers were washed withwater (200 mL), brine (200 mL), and dried over MgSO₄. After filtration,the filtrate was concentrated and the residue was dissolved intert-butyl dimethyl ether (150 mL), and cooled to −78° C. To this cooledsolution was added dropwise a solution of ethyl magnesium bromide (43.5mL, 1M in THF, 0.043 mol). The reaction was further stirred at −78° C.for 2.5 h and poured into ice cold water (200 mL) and neutralized with1N HCl (300 mL) to pH 6-7. The organic layer was collected and theaqueous layer was extracted with ethyl acetate (200 mL). The combinedorganic layers were washed with water (2×200 mL), saturated NaHCO₃(2×200 mL), water (100 mL) and brine (200 mL), and dried over MgSO₄.After filtration, the filtrate was concentrated and the residue waspurified on silica gel column using gradient 0 to 25% EtOAc in hexanesto give 3.0 g (30%) of desired product.

Step 2: To a solution of the product from Step 1 (3 g, 8 mmol) in THF(100 mL) at 0° C. was added NaH (0.5 g, 12 mmol) and the mixture wasstirred at 20° C. for 30 min. After cooling to 0° C., benzyl bromide(1.5 mL, 12 mmol) was added dropwise and heated to 70° C. for 16 h.After cooling, the reaction mixture was diluted with water (100 mL),acidified with acetic acid to pH 7-8 and was extracted with ethylacetate (2×200 mL). The combined organic layers were washed with water(200 mL), brine (200 mL), and dried over MgSO₄. After filtration, thefiltrate was concentrated and the residue was purified by flashchromatography (gradient 0 to 20% EtOAc in hexanes) to give 1.3 g (86%)of3,4-bis-benzyloxy-5-benzyloxymethyl-3-ethyl-2-methoxy-tetrahydro-furan.

MS (ES⁺) 463.25 (M+1).

Step 3: To a solution of the product from Step 2 (3.2 g, 6.9 mmol) indioxane (50 mL) was added 2 N HCl (50 mL) and heated at reflux for 20 h.The reaction mixture was allowed to attain room temperature and dilutedwith ethyl acetate (100 mL). The organic layer was collected and theaqueous layer was further extracted with ethyl acetate (100 mL). Thecombined organic layers were washed with water (2×100 mL), saturatedaqueous NaHCO₃ (50 mL), water (50 mL) and brine (50 mL), and dried overMgSO₄. After filtration, the filtrate was concentrated and the residuewas purified by flash chromatography (gradient 0 to 20% EtOAc inhexanes) to furnish 1.2 g (30%) of3,4-bis-benzyloxy-5-benzyloxymethyl-3-ethyl-tetrahydro-furan-2-ol, as anoil.

Step 4: To a stirred solution of sodium hydride (0.18 g, 5.4 mmol) anddiethyl (cyanomethyl)-phosphonate (0.85 mL, 5.4 mmol) in DME (20 mL) wasadded product from Step 3 (2.7 mmol, 1.2 g) and the reaction was stirredat room temperature for 16 h. The reaction was then diluted with diethylether (100 mL), washed with water (100 mL) and brine (100 mL). Theorganic layer was collected, dried over MgSO₄, filtered and the filtratewas concentrated to give 1.5 g of crude3,4-bis-benzyloxy-5-benzyloxymethyl-3-ethyl-tetrahydro-furan-2-yl)-acetonitrile,as an oil, which was used as such for the next step.

Example A-9

2-(4-(Trityloxymethyl)cyclopent-2-enyl)acetonitrile (Scheme A-7)

Step 1: To a stirred solution of(4-hydroxymethyl-cyclopent-2-enyl)-methanol (13.8 g, 107.81 mmol,prepared by method of Mekrami et al., Tetrahedron: Asymmetry 1992, 3,431) in methylene chloride (100 mL) was added pyridine (25.5 g, 118.59mmol) and trityl chloride (33.06 g, 118.59 mmol) at room temperature andthe mixture was stirred for 18 h. After addition of water (50 mL), thereaction mixture was diluted with methylene chloride (100 mL) and theorganic layer was separated. The aqueous layer was further extractedwith methylene chloride (100 mL). The combined organic layers werewashed with water (100 mL), brine (50 mL), and dried (MgSO₄). Afterfiltration, the filtrate was concentrated and the residue was purifiedon a silica gel column using ethyl acetate in hexanes (0 to 30%), whichafforded 18.25 g (45.7%) of desired product,(4-trityloxymethyl-cyclopent-2-enyl)-methanol.

¹HNMR (DMSO-d₆): δ 7.39-7.22 (m, 15H), 5.77-5.72 (m, 2H), 4.53 (t, J=5.4Hz, 1H, D₂O exchangeable), 3.22-3.18 (m, 2H), 2.93-2.84 (m, 3H),2.74-2.69 (m, 1H), 2.10 (m, 1H), 1.12-1.03 (m, 1H); MS (ES⁺) 393.47(M+23).

Step 2: To a stirred solution of product from Step 1 (18 g, 48.45 mmol)in pyridine (50 mL) was added p-toluenesulfonyl chloride at roomtemperature and the mixture was stirred for 48 h. After concentration,the residue was dissolved in ethylacetate (200 mL), washed with water(2×100 mL), brine (50 mL), and dried (MgSO₄). After filtration, thefiltrate was concentrated and the residue was purified on silica gelcolumn using ethyl acetate in hexanes (0 to 30%), which afforded 21.45 g(84.4%) of desired product, toluene-4-sulfonic acid4-trityloxymethyl-cyclopent-2-enylmethyl ester.

¹HNMR (DMSO-d₆): δ 7.69 (d, J=8.3 Hz, 2H), 7.40 (d, J=8.3 Hz, 2H),7.38-7.22 (m, 15H), 5.79 (d, J=5.4 Hz, 1H), 5.57 (d, J=5.6 Hz, 1H),3.91-3.77 (m, 2H), 2.94-2.83 (m, 4H), 2.37 (s, 3H), 2.09-1.98 (m, 1H),1.08-0.99 (m, 1H).

Step 3: To a stirred solution of compound from Step 2,toluene-4-sulfonic acid 4-trityloxymethyl-cyclopent-2-enylmethyl ester(21.3 g, 40.59 mmol) in dimethylformamide (150 mL) was added sodiumcyanide (3.58 g, 73.18 mmol) at room temperature and the reaction wasstirred at 70° C. for 48 h. After cooling, the reaction mixture wasextracted with ethyl acetate (2×250 mL), washed with water (2×100 mL),brine (50 mL) and dried (MgSO₄). After filtration, the filtrate wasconcentrated and the residue was purified on a silica gel column usingethyl acetate in hexanes (0 to 30%), which afforded 14.96 g (97.1%) ofdesired product, (4-trityloxymethyl-cyclopent-2-enyl)-acetonitrile, as acolorless solid.

¹HNMR (DMSO-d₆): δ 7.40-7.23 (m, 15H), 5.84 (d, J=5.1 Hz, 1H), 5.69 (d,J=5.4 Hz, 1H), 3.00-2.90 (m, 4H), 2.53 (d, J=6.4 Hz, 2H), 2.30-2.20 (m,1H), 1.16-1.07 (m, 1H).

Example A-10

2-(5-((tert-Butyldiphenylsilyloxy)methyl)-tetrahydrothiophen-2-yl)acetonitrile(Scheme A-8)

It was prepared from5-O-(tert-butyldiphenylsilyl)-2,3-dideoxy-4-thioribofuranose (SecristIII et al., J. Med. Chem. 1992, 35, 533) by following the same methodused in Example A-3, Step 3.

¹H NMR (CDCl₃) δ in ppm 7.70-7.40 (m, 10H), 4.10 (m, 1H), 3.65 (m, 3H),3.60 (m, 2H), 2.10 (m, 2H), 1.80 (m, 2H), 1.10 (s, 9H).

Example A-11

tert-Butyl6-((tert-butyldimethylsilyloxy)methyl)-4-(cyanomethyl)-2,2,3a-trimethyl-tetrahydro-[1,3]dioxolo[4,5-c]pyrrole-5-carboxylate

This was prepared by following the method reported in application Ser.No. 11/157,867 filed on Jun. 22, 2005.

Example B-1

7-β-(2′,3′,5′-Tri-O-benzyl-D-ribofuranosyl)-furo[3,2-d]pyrimidin-4(3H)-one(Scheme B-1)

Step 1: To a stirred solution of compound from Step 4 of example A-2,(3S,4R,5R)-(3,4-bis-benzyloxy-5-benzyloxymethyl-tetrahydro-furan-2-yl)-acetonitrile(10.7 g, 24.12 mmol) in DMF (150 mL) was addedtert-butoxybis(dimethylamino)methane (21.02 g, 120.62 mmol) at roomtemperature and stirred for 12 h. The reaction mixture was diluted withtoluene (700 mL) and washed with water (2×250 mL), brine (1×50 mL) anddried (MgSO₄). After filtration, the filtrate was concentrated to give(13.8 g) of desired product, which was used as such for next step.

Step 2: The compound from Step 1 (13.8 g, 24.12 mmol) was dissolved inchloroform (250 mL), trifluoroacetic acid (4.59 g, 40.29 mmol) and water(137 mL) at room temperature and stirred for 18 h. The organic layer wasseparated and the aqueous layer was extracted with chloroform (2×200mL). The combined organic extracts were washed with water (2×200 mL),brine (1×100 mL), and dried (MgSO₄). After filtration, the filtrate wasconcentrated to afford 12.59 g of desired product. A small amount wastaken out and purified on silica gel column using ethyl acetate andhexanes.

MS (ES⁺) 494.20 (M+23), (ES⁻) 470.28 (M−1); Anal. Calcd forC₂₉H₂₉NO₅.0.75H₂O: C, 71.80; H, 6.33; N, 2.88. Found: C, 71.95; H, 6.04;N, 2.88.

Step 3: To a stirred solution of product from Step 2, (186.5 g, 395.4mmol) in DMF (1500 mL) was added sodium hydride (19.7 g, 60%, 494.3mmol) in four portions at 0° C. over a period of 1.5 h followed by2-bromodiethylmalonate (118.1 g, 494.3 mmol) over a period of 30 min at0° C. and stirred at room temperature for 12 h. After diluting withwater (1000 mL), the reaction mixture was extracted with ethyl acetate(3×2000 mL). The combined organic extracts were washed with water(2×1000 mL), brine (1×200 mL), and dried (MgSO₄). After filtration, thefiltrate was concentrated to give 296 g of crude desired product, whichwas used in the next reaction without further purification.

Step 4: To a compound from Step 3 (296 g, crude) in EtOH (1000 mL) wasadded 1,5-diazabicyclo[4.3.0]non-5-ene (58.9 g, 474.48 mmol) at roomtemperature and stirred for 18 h. The reaction mixture was concentratedand the residue was dissolved in ethyl acetate (4000 mL), washed withwater (2×1000 mL), brine (2×500 mL), and dried (MgSO₄). Afterfiltration, the filtrate was concentrated and the crude residue waspurified by flash chromatography on silica gel using ethyl acetate andhexanes to afford 29 g, (13.1%) of the desired product as light brownoil.

Step 5: To a stirred solution of compound from Step 4 (29.0 g, 52.04mmol) in EtOH (600 mL) was added formamidine acetate (135 g, 1301 mmol)at room temperature and heated at reflux for four days and the solidmaterial was removed by filtration and filtrate was concentrated. Theresidue was dissolved in chloroform (400 mL), washed with water (2×100mL), brine (1×100 mL), and dried (MgSO₄). The crude residue was purifiedby flash chromatography on silica gel using CMA-80 in chloroform (0 to20%) to afford 12 g (42.8%) of the desired product (12 g, 42.8%) as acolorless crystalline solid; mp 88-100° C.

¹H NMR (DMSO-d₆): δ 12.66 (bs, 1H, D₂O exchangeable), 8.11 (s, 1H), 8.05(d, J=2.8 Hz, 1H), 7.33-7.25 (m, 15H), 5.11 (d, J=4.8 Hz, 1H), 4.61 (s,2H), 4.58-4.48 (m, 4H), 4.4 (t, J=4.7 Hz, 1H), 4.19-4.12 (m, 2H), 3.63(ddd, J=23.3, 10.7. 3.2 Hz, 2H); MS (ES⁺) 539.43 (M+1), 561.42 (M+23),(ES⁻) 537.44 (M−1); Anal. Calcd for C₃₂H₃₀N₂O₆: C, 71.36; H, 5.61; N,5.20. Found: C, 71.30; H, 5.54; N, 5.10.

Example B-2

4-Chloro-7-β-(2′,3′,5′-tri-O-benzyl-D-ribofuranosyl)-furo[3,2-d]pyrimidine(Scheme B-2)

To a stirred solution of compound from Example B-1, Step 5, (6.26 g,11.62 mmol), benzyltriethylammonium chloride (5.29 g, 23.24 mmol),N,N-dimethylaniline (2.12 g, 17.43 mmol) in acetonitrile (50 mL) wasadded phosphorous oxychloride (10.69 g, 69.74 mmol) at 80° C. andfurther stirred at 80° C. for 30 min. Then the reaction was concentratedto dryness, dissolved in chloroform (100 mL) and quenched with water (50mL). The organic layer was separated and aqueous layer was furtherextracted with chloroform (2×50 mL). The combined chloroform extractswere washed with water (2×100 mL), sat. NaHCO₃ (1×50 mL), water (1×100mL), and brine (1×50 mL), and dried (MgSO₄). After filtration, thefiltrate was concentrated and the residue was purified by flashchromatography on silica gel column using ethyl acetate in hexanes (0 to25%) to afford 5.62 g (86.8%) of desired product as a colorlesscrystalline solid.

¹H NMR (DMSO-d₆): δ 8.87 (s, 1H), 8.54 (s, 1H), 7.33-7.19 (m, 15H), 5.21(d, J=5.1 Hz, 1H), 4.66-4.47 (m, 7H), 4.24-4.18 (m, 2H), 3.66 (ddd,J=23.1, 10.5. 3.5 Hz, 2H); Anal. Calcd for C₃₂H₂₉ClN₂O₅: C, 68.99; H,5.24; Cl, 6.36; N, 5.02. Found: C, 69.12; H, 5.19; Cl, 6.30; N, 5.04.

Example B-3

4-Methylamino-7-β-(D-ribofuranosyl)-furo[3,2-d]pyrimidine (Scheme B-3)

Step 1: To a stirred solution of product from Example B-2 (0.5 g, 0.897mmol), methylamine hydrochloride (0.36 g, 5.38 mmol) in EtOH (10 mL) wasadded triethylamine (1.815 g, 17.94 mmol) at room temperature andstirred at 45° C. for 5 h and at room temperature for 12 h. The reactionmixture was concentrated to dryness, dissolved in chloroform (100 mL),washed with water (2×25 mL), brine (1×20 mL), and dried (MgSO₄). Afterfiltration, the filtrate was concentrated and the residue was purifiedon silica gel column using ethyl acetate in hexanes (0 to 50%) whichafforded 0.266 g (53.7%) of desired product as a colorless solid.

MS (ES⁺) 574.42 (M+23), (ES⁻) 550.72 (M−1).

Step 2: To a stirred solution of product from Step 1 (0.258 g, 0.468mmol) in methylene chloride (20 mL) was added boron trichloride (4.68mL, 4.68 mmol, 1M solution in methylene chloride) at −78° C. and stirredat the same temperature for 1 h. Then the reaction was brought to −30°C. over a period of 30 min, and quenched by adding a mixture ofmethanol:chloroform (2:1, 5 mL). After the reaction mixture reached toroom temperature, it was neutralized with aqueous NH₃ in MeOH (10%, 5mL) and was concentrated to dryness. The solid obtained was suspended inMeOH (15 mL) and 4N HCl in dioxane (2 mL) was added and reaction mixturewas concentrated. The residue was purified by flash chromatography onsilica gel using CMA-80 in chloroform (0 to 100%) which afforded 118 mg(89.6%) of the desired product as a colorless crystalline solid; mp88-100° C.

¹H NMR (DMSO-d₆): δ 8.30 (s, 1H), 8.21(s, 1H), 7.93 (d, J=4.7 Hz, 1H,D₂O exchangeable), 5.80 (dd, J=9.4, 3.3 Hz, 1H, D₂O exchangeable), 5.05(d, J=6.4 Hz, 1H, D₂O exchangeable), 4.88 (d, J=4.3 Hz, 1H), 4.77 (d,J=7.3, Hz, 1H, D₂O exchangeable), 4.35-4.29 (m, 1H), 1.04-4.00 (m, 1H),3.89 (dd, J=5.4, 2.6 Hz, 1H), 3.63 (td, J=12.0, 3.0 Hz, 1H), 3.52-3.44(m, 1H), 2.97 (d, J=4.5 Hz, 3H); IR (KBr) 3324.6, 2931.8, 1649.4,1557.1, 1520.0, 1442.4, 1403.8, 1332.5, 1221.1, 1180.1, 1101.5, 1080.1,1021.9, 956.9, 892.8, 821.7, 787.4, 742.6, 586.4 and 524.6 cm⁻¹; MS(ES⁺) 282.51 (M+1); Anal. Calcd for C₁₂H₁₅N₃O₅.0.6H₂O: C, 49.34; H,5.59; N, 14.38. Found: C, 49.41; H, 5.46; N, 14.06.

Example B-4

4-Ethylamino-7-β-(D-ribofuranosyl)-furo[3,2-d]pyrimidine (Scheme B-3)

This was prepared according to the procedure used for Example B-3, andusing ethylamine instead of methylamine, mp 76-88° C., yield 32% in twosteps.

¹H NMR (DMSO-d₆): δ 8.27 (s, 1H), 8.21 (s, 1H), 8.00 (t, J=5.8 Hz, 1H,D₂O exchangeable), 5.81 (d, J=10.1 Hz, 1H, D₂O exchangeable), 5.04 (d,J=7.62 Hz, 1H, D₂O exchangeable), 4.68 (d, J=6.2 Hz, 1H, D₂Oexchangeable), 4.76 (d, J=7.3 Hz, 1H), 4.35-4.29 (m, 1H), 4.04-4.00 (m,1H), 3.89 (dd, J=5.4, 2.8 Hz, 1H), 3.63 (d, J=13.1 Hz, 1H), 3.54-3.46(m, 3H), 1.18 (t, J=7.15 Hz, 3H); IR (KBr) 3427.5, 3249.4, 3110.9,2926.5, 2874.6, 2779.2, 2618.3, 2525.0, 1640.4, 1558.5, 1502.9, 1419.6,1330.9, 1249.9, 1224.2, 1171.3, 1118.7, 1082.5, 1014.6, 900.8, 853.2,749.5, 653.9, 653.6, 588.3 and 547.8 cm⁻¹; MS (ES⁺) 296.52 (M+1); Anal.Calcd for C₁₃H₁₇N₃O₅.H₂O.0.25CH₃OH: C, 49.52; H, 6.27; N, 13.07. Found:C, 49.83; H, 5.99; N, 12.80.

Example B-5

4-Isopropylamino-7-β-(D-ribofuranosyl)-furo[3,2-d]pyrimidine (SchemeB-3)

This was prepared according to the procedure used for Example B-3, andusing isopropylamine instead of methylamine, mp 58-80° C., yield 32% intwo steps.

¹H NMR (DMSO-d₆): δ 8.27 (s, 1H), 8.21 (s, 1H), 7.84 (d, J=8.1 Hz, 1H,D₂O exchangeable), 5.83 (bs, 1H, D₂O exchangeable), 5.03 (d, J=6.4 Hz,1H, D₂O exchangeable), 4.88 (d, J=4.3 Hz, 1H, D₂O exchangeable), 4.76(d, J=7.3 Hz, 1H), 4.45-4.29 (m, 2H), 4.04-4.00 (m, 1H), 3.89 (dd,J=5.2, 2.6 Hz, 1H), 3.63 (dd, J=12.0, 2.6 Hz, 1H), 3.53-3.44 (m, 1H),1.21 (d, J=6.5 Hz, 6H); IR (KBr) 3300.2, 2973.9, 2928.4, 1637.7, 1557.4,1502.5, 1450.5, 1423.5, 1332.4, 1217.8, 1176.6, 1120.7, 1086.5, 1020.8,892.4, 821.7, 700.4, 588.3 and 537.6 cm⁻¹; MS (ES⁻) 308 (M−1); Anal.Calcd for C₁₄H₁₉N₃O₅.0.8H₂O: C, 51.94; H, 6.41; N, 12.98. Found: C,52.24; H, 6.41; N, 12.50.

Example B-6

4-Dimethylamino-7-β-(D-ribofuranosyl)-furo[3,2-d]pyrimidine (Scheme B-3)

This was prepared according to the procedure used for Example B-3, andusing dimethylamine instead of methylamine, mp 210° C., yield 45% in twosteps.

¹H NMR (DMSO-d₆): δ 8.29 (s, 1H), 8.24 (s, 1H), 5.76 (dd, J=9.4, 3.4 Hz,1H, D₂O exchangeable), 5.05 (d, J=6.2 Hz, 1H, D₂O exchangeable), 4.88(d, J=4.5 Hz, 1H, D₂O exchangeable), 4.78 (d, J=7.3 Hz; 1H), 4.35-4.29(m, 1H), 4.04-4.00 (m, 1H), 3.89 (dd, J=5.8, 3.0 Hz, 1H), 3.63 (dd,J=12.4, 3.4 Hz, 1H), 3.52-3.44 (m, 1H), 3.33 (s, 6H); IR (KBr) 3361.4,3120.5, 2972.9, 2930.6, 2865.1, 1627.5, 1515.9, 1428.7, 1406.1, 1368.8,1348.9, 1304.8, 1275.0, 1224.0, 1115.1, 1098.3, 1081.7, 1018.5, 869.3,848.3, 748.2 and 593.3 cm⁻¹; MS (ES⁺) 296.51 (M+1); Anal. Calcd forC₁₃H₁₇N₃O₅: C, 52.87; H, 5.80; N, 14.23. Found: C, 52.80; H, 5.87; N,14.07.

Example B-7

4-n-Propylamino-7-β-(D-ribofuranosyl)-furo[3,2-d]pyrimidine (Scheme B-3)

This was prepared according to the procedure used for Example B-3, andusing propylamine instead of methylamine, mp 58-80° C., yield 21% in twosteps.

¹H NMR (DMSO-d₆): δ 8.27 (s, 1H), 8.21 (s, 1H), 8.03 (bs, 1H, D₂Oexchangeable), 5.81 (dd, J=9.8, 3.4 Hz, 1H, D₂O exchangeable), 5.04 (d,J=6.4 Hz, 1H, D₂O exchangeable), 4.88 (d, J=4.3 Hz, 1H, D₂Oexchangeable), 4.76 (d, J=7.3 Hz, 1H), 4.36-4.29 (m, 1H), 4.04-4.00 (m,1H), 3.89 (dd, J=5.4, 2.6 Hz, 1H), 3.65-3.60 (m, 1H), 3.52-3.40 (m, 3H),1.65-1.54 (m, 2H), 0.90 (t, J=7.3 Hz, 3H); IR (KBr) 3310.5, 2931.8,2207.9, 1911.5, 1640.7, 1557.6, 1510.3, 1422.2, 1333.6, 1304.4, 1238.3,1170.5, 1116.8, 1082.1, 1020.2, 891.1, 821.7, 746.4 and 586.4 cm⁻¹; MS(ES⁺) 310 (M+1), (ES⁻) 308.48 (M−1); Anal. Calcd for C₁₄H₁₉N₃O₅.0.75H₂O:C, 52.08; H, 6.40; N, 13.01. Found: C, 52.10; H, 6.08; N, 12.62.

Example B-8

4-Cyclopropylamino-7-β-(D-ribofuranosyl)-furo[3,2-d]pyrimidine (SchemeB-3)

This was prepared according to the procedure used for Example B-3, andusing cyclopropylamine instead of methylamine, mp 88-100° C., yield 44%in two steps.

¹H NMR (DMSO-d₆): δ 8.31 (s, 1H), 8.23 (s, 1H), 8.14 (d, J=3.5 Hz, 1H,D₂O exchangeable), 5.77 (dd, J=9.4, 3.4 Hz, 1H, D₂O exchangeable), 5.05(d, J=6.4 Hz, 1H, D₂O exchangeable), 4.88 (d, J=4.3 Hz, 1H, D₂Oexchangeable), 4.77 (d, J=7.3 Hz, 1H), 4.36-4.29 (m, 1H), 4.04-4.00 (m,1H), 3.89 (dd, J=5.8, 3.2 Hz, 1H), 3.63-3.44 (m, 2H), 3.01-2.92 (m, 1H),0.79-0.73 (m, 2H), 0.62-0.57 (m, 2H); IR (KBr) 3295.5, 2924.1, 2189.0,1640.2, 1557.4, 1502.5, 1425.4, 1354.4, 1300.6, 1227.4, 1120.1, 1086.2,1022.1, 892.7, 824.1, 787.0, 744.3, 702.1, 589.2 and 534.3 cm⁻¹; MS(ES⁺) 308.52 (M+1), (ES⁻) 306.46 (M−1); Anal. Calcd for C₁₄H₁₇N₃O₅.H₂O:C, 51.68; H, 5.88; N, 12.91. Found: C, 51.89; H, 5.80; N, 12.59.

Example B-9

4-Azetidino-7-β-(D-ribofuranosyl)-furo[3,2-d]pyrimidine (Scheme B-3)

This was prepared according to the procedure used for Example B-3, andusing azetidine instead of methylamine, mp 192° C., yield 56% in twosteps.

¹H NMR (DMSO-d₆): δ 8.28 (s, 1H), 8.23 (s, 1H), 5.72 (dd, J=9.2, 3.2 Hz,1H, D₂O exchangeable), 5.04 (d, J=6.4 Hz, 1H, D₂O exchangeable), 4.88(d, J=4.5 Hz, 1H, D₂O exchangeable), 4.77 (d, J=7.3 Hz, 1H), 4.35-4.28(m, 5H), 4.03-3.99 (m, 1H), 3.88 (dd, J=5.8, 3.0 Hz, 1H), 3.65-3.44 (m,2H), 2.49-2.40 (m, 2H); IR (KBr) 3413.0, 3211.5, 3062.0, 2943.4, 2879.7,2650.0, 1896.7, 1633.2, 1592.4, 1547.5, 1508.3, 1440.8, 1401.7, 1340.3,1296.8, 1244.1, 1213.4, 1171.9, 1118.7, 1082.1, 1013.0, 974.1, 904.6,866.0, 818.3, 787.4, 748.4, 687.9, 663.5 and 590.1 cm⁻¹; MS (ES⁺) 308.52(M+1); Anal. Calcd for C₁₄H₁₇N₃O₅.0.15H₂O: C, 54.24; H, 5.62; N, 13.55.Found: C, 54.27; H, 5.56; N, 13.41.

Example B-10

4-Pyrrolidino-7-β-(D-ribofuranosyl)-furo[3,2-d]pyrimidine (Scheme B-3)

This was prepared according to the procedure used for Example B-3, andusing pyrrolidine instead of methylamine, mp 198° C., yield 54% in twosteps.

¹H NMR (DMSO-d₆): δ 8.33 (s, 1H), 8.29 (s, 1H), 5.91 (bs, 1H, D₂Oexchangeable), 5.11 (d, J=6.2 Hz, 1H, D₂O exchangeable), 4.95 (d, J=4.3Hz, 1H, D₂O exchangeable), 4.84 (d, J=7.3 Hz, 1H), 4.41-4.35 (m, 1H),4.10-4.01 (m, 1H), 3.96 (dd, J=5.8, 3.0 Hz, 1H), 3.94-3.67 (m, 5H),3.58-3.51 (m, 1H), 2.07-1.97 (bs, 4H); IR (KBr) 3456.4, 3261.6, 3113.1,2949.2, 2914.8, 2871.0, 2794.8, 2629.6, 1624.6, 1544.8, 1501.3, 1456.3,1345.9, 1325.1, 1252.8, 1229.2, 1188.3, 1117.7, 1087.7, 1014.5, 980.4,901.1, 846.7, 787.1, 748.4, 633.4, 588.3 and 545.9 cm⁻¹; MS (ES⁺) 322.54(M+1); Anal. Calcd for C₁₅H₁₉N₃O₅.0.25H₂O: C, 55.29; H, 6.03; N, 12.89.Found: C, 55.53; H, 6.01; N, 12.72.

Example B-11

7-β-(2′,3′,5′-Tri-O-benzyl-2′-C-methyl-D-ribofuranosyl)-furo[3,2-d]pyrimidin-4(3H)-one(Scheme B-1)

This was prepared according to the procedure used for Example B-1,starting from Example A-5 instead of A-2.

¹H NMR (DMSO-d₆): δ 12.67 (bs, 1H, D₂O exchangeable), 8.14 (s, 1H), 8.09(s, 1H), 7.38-7.25 (m, 15H), 5.21 (s, 1H), 4.75-4.52 (m, 6H), 4.2-4.15(m, 1H), 4.05 (d, J=7.72 Hz, 1H), 3.78-3.68 (m, 2H), 1.21 (s, 3H); MS(ES⁺) 553.37 (M+1); Anal. Calcd for C₃₃H₃₂N₂O₆: C, 71.72; H, 5.84; N,5.07. Found: C, 71.51; H, 5.89; N, 5.07.

Example B-12

4-Chloro-7-β-(2′,3′,5′-tri-O-benzyl-2′-C-methyl-D-ribofuranosyl)-furo[3,2-d]pyrimidine(Scheme B-2)

This was prepared according to the procedure used for Example B-2, usingstarting material from Example B-11 instead of B-1, yield 92%.

¹H NMR (DMSO-d₆): δ 8.98 (s, 1H), 8.57 (s, 1H), 7.38-7.24 (m, 15H), 5.31(s, 1H), 4.70 (dd, J=16.7, 11.6 Hz, 2H), 4.67-4.53 (m, 4H), 4.24-4.19(m, 1H), 4.10 (d, J=7.5 Hz, 1H), 3.75 (ddd, J=21.8, 10.9, 3.2 Hz, 2H),1.21 (s, 3H); Anal. Calcd for C₃₃H₃₁ClN₂O₅: C, 69.40; H, 5.47; N, 4.90.Found: C, 69.65; H, 5.48; N, 4.92.

Example B-13

4-Methoxy-7-β-(2′-C-methyl-D-ribofuranosyl)-furo[3,2-d]pyrimidine(Scheme B-3)

Step 1: To a stirred solution of freshly prepared sodium methoxide{prepared from Na (0.022 g, 3.27 mmol) in MeOH (5 mL)} was addedcompound from Example B-12 (0.187 g, 0.327 mmol) in methanol (5 mL) atroom temperature and further stirred for 2 h. After concentrating thereaction mixture, the residue was suspended in water (15 mL) andextracted with ethylacetate (2×50 mL). The combined organic extractswere washed with water (2×20 mL), brine (20 mL), and dried (MgSO₄).After filtration, the filtrate was concentrated and the residue waspurified on a silica gel column, which gave 157 mg (84%) of desiredproduct as a colorless sticky material.

¹H NMR (DMSO-d₆): δ 8.65 (s, 1H), 8.30 (d, J=0.5 Hz, 1H), 7.40-7.25 (m,15H), 5.29 (d, J=0.5 Hz, 1H), 4.71 (dd, J=15.6, 11.6 Hz, 2H), 4.63 (dd,J=15.4, 11.5 Hz, 2H), 4.57 (dd, J=16.4, 11.8 Hz, 2H), 4.23-4.18 (m, 1H),4.12 (d, J=7.9 Hz, 1H), 4.10 (s, 3H), 3.79 (dd, J=10.9, 3.2 Hz, 1H),3.71 (dd, J=10.7, 4.5 Hz, 1H), 1.19 (s, 3H); MS (ES⁺) 567.39 (M+1),589.37 (M+23).

Step 2: To a suspension of 10% Pd—C (0.05 g) in methanol (3 mL) wasadded a solution of compound from Step 1 (0.15 g, 0.264 mmol) in MeOH(10 mL) followed by 1N HCl (0.79 mL, 0.79 mmol). The mixture washydrogenated at 60 psi for 6 h and filtered through a small pad ofCelite and the filtrate was concentrated to dryness. The residue waspurified on a column of silica gel using CMA-80 in chloroform (0 to10%), which afforded 65 mg (83.1%) of desired product as a colorlesssolid.

¹H NMR (DMSO-d₆): δ 8.64 (s, 1H), 8.37 (d, J=0.8 Hz, 1H), 5.02 (d, J=0.8Hz, 1H), 5.01 (d, 1H, D₂O exchangeable), 4.88 (dd, J=6.0, 4.7 Hz, 1H,D₂O exchangeable), 4.78 (s, 1H, D₂O exchangeable), 4.10 (s, 3H),3.88-3.83 (m, 1H), 3.81-3.72 (m, 2H), 3.64-3.57 (m, 1H), 0.90 (s, 3H);IR (KBr): 3399.7, 2926.2, 1623.4, 1552.7, 1486.2, 1444.1, 1371.7,1321.0, 1226.8, 1184.9, 1154.3, 1105.2, 1076.1, 1045.8, 925.4, 870.1,835.2, 796.6, 698.3, 642.4 and 591.1 cm−1; MS (ES⁺) 297.44 (M+1); Anal.Calcd for C₁₃H₁₆N₂O₆.0.25H₂O: C, 51.91; H, 5.52; N, 9.31. Found: C,52.09; H, 5.65; N, 9.09.

Example B-14

4-[(N-1-Hydroxyethyl)hydrazino]-7-β-(2′-C-methyl-D-ribofuranosyl)-furo[3,2-d]pyrimidine(Scheme B-3)

Step 1: To a stirred solution of compound from Example B-12 (0.2 g, 0.35mmol) in ethanol (10 mL) and chloroform (5 mL) was addedN-hydroxyethylhydrazine (0.079 g, 1.05 mmol) at room temperature andstirred for 48 h. After concentrating the reaction mixture, the residuewas diluted with water (10 mL) and extracted with chloroform (3×20 mL).The combined organic extracts were washed with brine (10 mL) and dried(MgSO₄). After filtration, the filtrate was concentrated and the residuewas purified on silica gel column using methanol in chloroform (0 to5%), which afforded 186 mg (87.1%) of desired product.

¹H NMR (DMSO-d₆): δ 8.29 (s, 1H), 8.13 (s, 1H), 7.39-7.25 (m, 15H), 5.26(s, 1H), 5.13 (s, 2H, D₂O exchangeable), 4.75 (t, J=5.4 Hz, 1H, D₂Oexchangeable), 4.73-4.53 (m, 6H), 4.20-4.11 (m, 2H), 3.88 (t, J=6.4 Hz,2H), 3.78 (dd, J=10.9, 2.6 Hz, 1H), 3.72-3.67 (m, 3H), 1.20 (s, 3H); MS,(ES⁻) 609.28 (M−1).

Step 2: To a stirred solution of compound from Step 1 (180 mg, 0.29mmol) in methylene chloride (20 mL) was added 1M solution of borontrichloride in dichloromethane (2.95 mL, 2.95 mmol) at −78° C. andstirred further at this temperature for 1.5 h. After the temperaturebecame 0° C., it was quenched by adding chloroform (2 mL) and methanol(3 mL). To the mixture was added aqueous saturated ammonia (5 mL) and itwas stirred for 30 min at room temperature. After concentration, theresidue was dissolved in methanol (10 mL), treated with 1M dry HCl inmethanol (2 mL) and stirred for 1 h. The resultant suspension wasconcentrated to dryness and the residue was purified on a silica gelcolumn using CMA-80 in chloroform (0 to 10%), which afforded 68 mg(68.8%) of desired product as a colorless solid; mp 84-92° C.

¹H NMR (DMSO-d₆): δ 8.25 (s, 1H), 8.17 (s, 1H), 5.16 (bs, 3H, D₂Oexchangeable), 4.99-4.95 (m, 2H, D₂O exchangeable), 4.80 (s, 1H),4.77-4.73 (m, 1H, D₂O exchangeable), 3.92-3.86 (m, 3H), 3.80-3.66 (m,4H), 3.63-3.55 (m, 1H), 0.89 (s, 3H); IR (KBr) 3412.8, 2926.0, 1612.5,1577.1, 1539.9, 1487.4, 1437.0, 1352.1, 1305.8, 1072.4, 1045.4, 830.3,788.9, 634.6 and 588.3 cm⁻¹; MS (ES⁺) 341.39 (M+1), 363.37 (M+23), (ES⁻)339.36 (M−1); Anal. Calcd for C₁₄H₂₀N₄O₆.0.25H₂O: C, 48.76; H, 5.99; N,16.24. Found: C, 49.01; H, 6.08; N, 15.71.

Example B-15

4-[(N-1-Methyl)hydrazino]-7-β-(2′-C-methyl-D-ribofuranosyl)-furo[3,2-d]pyrimidine(Scheme B-3)

Step-1: This was prepared according to the procedure used for ExampleB-14 (Step 1), using N-methylhydrazine instead ofN-hydroxyethylhydrazine, yield 89%.

¹H NMR (DMSO-d₆): δ 8.29 (s, 1H), 8.12 (d, J=0.7 Hz, 1H), 7.38-7.25 (m,15H), 5.25 (s, 1H), 5.20 (s, 2H, D₂O exchangeable), 4.72 (s, 2H),4.68-4.53 (m, 4H), 4.20-4.10 (m, 2H), 3.74 (ddd, J=23.7, 10.7, 2.6 Hz,2H), 3.37 (s, 3H), 1.19 (s, 3H); MS (ES⁺) 581.36 (M+1), 603.31 (M+23).

Step 2: This was prepared according to the procedure used for ExampleB-2 (Step 2), using product from Step 1; mp 70-84° C., yield 87%.

¹H NMR (DMSO-d₆): δ 8.25 (d, J=0.56 Hz, 1H), 8.16 (s, 1H), 5.23 (s, 2H,D₂O exchangeable), 5.06 (dd, J=6.7, 4.7 Hz, 1H, D₂O exchangeable), 4.96(d, J=7.5 Hz, 2H, D₂O exchangeable), 4.80 (s, 1H), 3.90 (dd, J=8.66, 6.9Hz, 1H), 3.80-3.71 (m, 2H), 3.64-3.56 (m, 1H), 3.37 (s, 3H), 0.88 (s,3H); IR (KBr): 3821.1, 2926.6, 1663.4, 1615.1, 1581.2, 1537.3, 1497.4,1441.6, 1413.8, 1355.9, 1306.4, 1109.1, 1074.3, 1041.6, 957.8, 868.0,835.2, 790.1, 636.5 and 589.0 cm⁻¹; M; MS (ES⁺) 311.49 (M+1), 333.45(M+23), (ES⁻) 309.45 (M−1); Anal. Calcd for C₁₃H₁₈N₄O₅I.0.25H₂O: C,49.59; H, 5.92; N, 17.79. Found: C, 49.76; H, 6.13; N, 16.97.

Example B-16

4-Dimethylamino-7-β-(2′-C-methyl-D-ribofuranosyl)-furo[3,2-d]pyrimidine(Scheme B-3)

Step 1: To a stirred solution of compound from Example B-12 (0.11 g,0.19 mmol) was added 40% solution of N,N-dimethylamine in water (5 mL)at room temperature and was stirred at same temperature for 18 h. Afterconcentrating the reaction mixture, the residue was purified on a columnof silica gel using ethyl acetate and hexanes mixture as eluent toafford 106 mg (96.3%) of desired product.

¹H NMR (DMSO-d₆): δ 8.32 (s, 1H), 8.14 (s, 1H), 7.37-7.25 (m, 15H), 5.25(s, 1H), 4.72-4.52 (m, 6H), 4.19-4.11 (m, 2H), 3.78 (dd, J=10.7, 2.6 Hz,1H), 3.69(dd, J-10.9, 3.9 Hz, 1H), 3.30 (bs, 6H), 1.20 (s, 3H); MS (ES⁺)580.34 (M+1), 602.40 (M+23); Anal. Calcd for C₃₅H₃₇N₃O₅: C, 72.51; H,6.43; N, 7.24. Found: C, 72.42; H, 6.56; N, 7.17.

Step 2: To a suspension of 10% Pd—C (20 mg) in methanol (3 mL) was addeda solution of compound from Step 1 (0.09 g, 0.155 mmol) in MeOH (20 mL)followed by 1N HCl (1 mL, 1 mmol). The mixture was hydrogenated at 70psi for 3 h and filtered through a small pad of Celite and the filtratewas concentrated to dryness. The residue was dissolved in methanol (2mL) and triturated with ether (2×3 mL). The solid was separated andcollected by filtration to afford 40 mg (83.4%) of desired product as acolorless solid.

¹H NMR (DMSO-d₆-D₂O): δ 8.57 (s, 1H), 8.41 (s, 1H), 4.99 (s, 1H),3.84-3.60 (m, 4H), 3.45 (bs, 6H), 0.87 (s, 3H); MS (ES⁺) 310.38 (M+1);Anal. Calcd for C₁₄H₁₉N₃O₅.3HCl.1.5H₂O.0.15Et₂O: C, 38.38; H, 5.84; N,9.19. Found: C, 38.29; H, 5.50; N, 8.95.

Example B-17

4-Methylamino-7-β-(2′-C-methyl-D-ribofuranosyl)-furo[3,2-d]pyrimidine(Scheme B-3)

This was prepared according to the procedure used for Example B-16,using methylamine instead of dimethylamine, yield 63% in two steps.

¹H NMR (DMSO-d₆): δ 8.30 (s, 1H), 8.16(s, 1H), 7.84 (d, 1H, D₂Oexchangeable), 5.07 (dd, J=6.5, 4.5 Hz, 1H, D₂O exchangeable), 4.97 (d,J=6.5 Hz, 1H, D₂O exchangeable), 4.96 (s, 1H), 4.77 (s, 1H, D₂Oexchangeable), 3.92 (dd, J=8.4, 6.9 Hz, 1H), 3.80-3.72 (m, 2H),3.64-3.56 (m, 1H), 2.95 (d, J=4.5 Hz, 3H), 0.89 (s, 3H); MS (ES⁺) 296.51(M+1), 318.45 (M+23), (ES⁻) 294.47 (M−1).

Example B-18

4-Aminoethylamino-7-β-(2′-C-methyl-D-ribofuranosyl)-furo[3,2-d]pyrimidine(Scheme B-3)

Step 1: A solution of compound from Example B-12 (212 mg, 0.37 mmol) inethanol (15 mL) and chloroform (15 mL) was treated withethane-1,2-diamine (0.5 mL, 7.4 mmol) followed by stirring at roomtemperature for 16 h. Additional ethane-1,2-diamine (0.25 mL, 3.7 mmol)was added and stirring was continued for 6 h. The reaction mixture wasconcentrated and purified on a silica gel column using chloroform/CMA-80(1:0 to 0:1) as eluent to give 157 mg (71%) of desired product as alight yellow oil.

¹H NMR (MeOH-d₄): δ 8.31 (s, 1H), 8.05 (d, J=0.7 Hz, 1H), 7.44-7.20 (m,15H), 5.37 (d, J=0.7 Hz, 1H), 4:79 (s, 2H), 4.64 (s, 2H), 4.64-4.50 (m,2H), 4.34-4.26 (m, 1H), 4.15 (d, J=7.9 Hz, 1H), 3.88-3.60 (m, 2H), 3.65(t, J=6.2 Hz, 2H), 2.93 (t, J=6.2 Hz, 2H), 1.19 (s, 3H); IR (neat,cm⁻¹): 3363, 2867, 1635, 1497, 1090; MS (ES⁺) 595.46 (M+H)⁺ Anal. Calcdfor C₃₅H₃₈N₄O₅.0.5H₂O: C, 69.63; H, 6.51; N, 9.28. Found: C, 69.59; H,6.46; N, 9.22.

Step 2: A solution of product from Step 1 (120 mg, 0.20 mmol) indichloromethane (3.7 mL) was cooled to −78° C. and treated with BCl₃dropwise (1M in dichloromethane, 2.0 mL) followed by stirring at −78° C.for 2 h and at −25° C. for 2 h. The reaction mixture was treated withCH₂Cl₂:MeOH (1:1, 2.2 mL) and stirred at −15° C. for 0.5 h. It was thenneutralized with conc. NH₄OH at 0° C. and stirred at room temperaturefor 15 min followed by concentration under vacuum. The residue wastreated with MeOH (12 mL) and 20% HCl in MeOH (15 mL) and stirred atroom temperature for 1 h followed by concentration. The residue waspurified on a silica gel column using CMA-80:CMA-50 (1:0 to 1:1) aseluent to give 62 mg (96%) of desired product as a yellow solid.

¹H NMR (MeOH-d₄): δ 8.39 (s, 1H), 8.09 (d, J=0.9 Hz, 1H), 5.12 (d, J=0.9Hz, 1H), 4.04-3.78 (m, 4H), 3.91 (t, J=5.8 Hz, 2H), 3.28 (t, J=5.8 Hz,2H), 1.02 (s, 3H); IR (KBr, cm⁻¹) 3367, 1642, 1507, 1410, 1075; MS (ES⁺)325.46 (M+H)⁺.

Example B-19

4-Hydrazino-7-β-(2′-C-methyl-D-ribofuranosyl)-furo[3,2-d]pyrimidine(Scheme B-3)

Step 1: A solution of compound from Example B-12 (219 mg, 0.38 mmol) inethanol (15 mL) and chloroform (15 mL) was treated with hydrazine (98%,0.05 mL, 1.56 mmol) followed by stirring at room temperature for 16 h.Additional hydrazine (0.10 mL, 3.12 mmol) was added and stirring wascontinued for 23 h. The reaction mixture was concentrated and purifiedon a silica gel column using chloroform/CMA-80 (1:0 to 2:1) as eluent togive 129 mg (60%) of desired product as an off-white solid.

¹H NMR (MeOH-d₄): δ 8.37 (s, 1H), 8.07 (d, J=0.9 Hz, 1H), 7.45-7.20 (m,15H), 5.39 (d, J=0.9 Hz, 1H), 4.81 (s, 2H), 4.70-4.54 (m, 4H), 4.34-4.27(m, 1H), 4.17 (d, J=7.9 Hz, 1H), 3.90-3.71 (m, 2H), 1.21 (s, 3H); IR(neat, cm⁻¹) 3316, 3030, 2895, 1624, 1453, 1088; MS (ES⁺) 567.44 (M+H)⁺;Anal. Calcd for C₃₃H₃₄N₄O₅: C, 69.95; H, 6.05; N, 9.89. Found: C, 69.86;H, 6.02; N, 9.69.

Step 2: A solution of compound from Step 1 (98 mg, 0.17 mmol) indichloromethane (3.1 mL) was cooled to −78° C. and treated with BCl₃ (1Min dichloromethane, 1.7 mL) dropwise followed by further stirring at−78° C. for 2 h and at −25° C. for 2 h. The reaction mixture was treatedwith CH₂Cl₂/MeOH (1:1, 1.9 mL) and stirred at −15° C. for 0.5 h. It wasthen neutralized with conc. NH₄OH at 0° C. and stirred at roomtemperature for 15 min followed by concentration under vacuum. Theresidue was treated with MeOH (10 mL) and 20% HCl in MeOH (12.5 mL) andstirred at room temperature for 1 h followed by concentration. Theresidue was purified on a silica gel column using chloroform/CMA-80 (1:0to 0:1) as eluent to give 32 mg (64%) of desired product as a lightbrown solid.

¹H NMR (MeOH-d₄): δ 8.04 (s, 1H), 7.79 (s, 1H), 4.94 (s, 1H), 3.92-3.64(m, 4H), 0.82 (s, 3H); IR (KBr, cm⁻¹): 3316, 2927, 1634, 1072; MS (ES⁺):297.47 (M+H)⁺.

Example B-20

((2S,5R)-(5-(4-Aminofuro[3,2-d]pyrimidin-7-yl)-4-methyl-2,5-dihydrofuran-2-yl)methanol(Scheme B-6)

Step 1: To a solution of compound from Example A-7 (Step 7) (55 g, 0.139mmol) in DMF (695 mL) was added tert-butoxybis(dimethylamino)methane (73g, 0.417 mmol) and heated at 60° C. for 6 h. After evaporating most ofthe solvent under reduced pressure, the residue was suspended in water(500 mL) and extracted with Et₂O (3×350 mL). Combined organic extractswere washed with water (2×250 mL), dried over MgSO₄, filtered and thefiltrate was concentrated to give 72 g of desired product,dimethyl-[2-(3-methyl-5-trityloxymethyl-2,5-dihydro-furan-2-yl)-propenyl]-amine,which was used as such for the next step.

Step 2: To a solution of compound from Step 1 (70 g crude) in CHCl₃(1200 mL), was added water (750 mL) followed by trifluoroacetic acid (17mL). The reaction mixture was stirred at room temperature for 17 h andthe organic layer was separated. The aqueous layer was further extractedwith CHCl₃ (200 mL) and the combined organic layers were washed withwater (500 mL), sat. NaHCO₃ (200 mL), and dried over MgSO₄. Afterfiltration, the filtrate was concentrated to give 48 g of thecorresponding enol. This was used as such in the next step.

Step 3: To a stirring suspension of the compound obtained from Step 2(47 g crude), DMF (1000 mL), KF (12.8 g, 0.22 mol) and 18-crown-6 (23 g,0.088 mol) was added chloroacetonitrile (25 g, 0.333 mol) and thereaction mixture was stirred for 24 h at room temperature. Afterremoving most of the solvent under reduced pressure, water (1000 mL) wasadded and the mixture was extracted with Et₂O (2×700 mL). The combinedorganic extracts were washed with water (2×250 mL), dried over MgSO₄,and filtered. The filtrate was concentrated and the residue was purifiedon a column of silica gel (450 g) using 10 to 40% EtOAc in hexanes togive 21 g (32% in three steps) of corresponding cyanomethyl enol ether.

MS (ES⁺) 485.21 (M+Na).

Step 4: To a cold solution (−78° C.) of the compound obtained from Step3 in THF (530 mL) was added LDA (2M in THF, 65 mL) at such a rate thatthe reaction temperature never exceeded above −70° C. After another 0.5h stirring at −78° C., the reaction mixture was quenched with water (50mL) and allowed to attain room temperature. After removing the solvent,the residue was purified on a silica gel column (450 g) using 0 to 20%EtOAc in hexanes as eluent. Two more successive column chromatographywere needed to purify the compound and to give 3.02 g (15%) of3-amino-4-((2S)-3-methyl-5-(trityloxymethyl)-2,5-dihydrofuran-2-yl)furan-2-carbonitrile,as a white solid; mp 68° C. (R_(f)=0.5 in 30% EtOAc in hexanes).

¹H NMR (DMSO-d₆): 7.62 (s, 1H), 7.23-7.42 (m, 15H), 5.56-5.68 (m, 4H),5.07 (m, 1H), 2.96 (m, 2H), 1.62 (s, 3H).); IR (KBr): 3357, 2864, 2203,1635, 1444, 1071, 704 cm⁻¹; MS (ES⁺) 485.34 (M+Na); Anal. Calcd forC₃₀H₂₆N₂O₃: C, 77.90; H, 5.66; N, 6.05. Found: C, 77.59; H, 5.75; N,5.85.

Further elution provided 2.17 g (11%) of3-amino-4-((2R)-3-methyl-5-(trityloxymethyl)-2,5-dihydrofuran-2-yl)furan-2-carbonitrileas a white solid, mp 138-144° C. (R_(f)=0.48 in 30% EtOAc in hexanes).

¹H NMR (DMSO-d₆): 7.20-7.40 (m, 16H), 5.87 (br, 2H), 5.65 (m, 1H), 5.53(m, 1H), 4.86 (m, 1H), 3.06 (dd, J=9.6 and 6.7 Hz, 1H), 2.9 (dd, J=9.6and 3.0 Hz, 1H) 1.66 (s, 3H); IR (KBr): 3361, 2868, 2201, 1637, 1444,1085, 700 cm⁻¹; MS (ES⁺) 485.28 (M+Na); Anal. Calcd for C₃₀H₂₆N₂O₃: C,77.90; H, 5.66; N, 6.05. Found: C, 77.72; H, 5.75; N, 5.93.

Step 5: A mixture of compound from Step 4,3-amino-4-((2R)-3-methyl-5-(trityloxymethyl)-2,5-dihydrofuran-2-yl)furan-2-carbonitrile(1.45 g, 3.13 mol) and formamidine acetate (6.5 g, 62.69 mmol) in EtOH(25 mL) was heated at reflux for 24 h. Additional formamidine acetate(3.25 g, 31.34 mmol) was added and continued heating for further 40 h.Most of the solvent was evaporated, water (100 mL) was added and themixture was extracted with EtOAc (2×75 mL). The combined organicextracts were washed with water (2×50 mL), dried over MgSO₄ andfiltered. The filtrate was concentrated and the residue was purified ona silica gel column (40 g) using 0 to 10% EtOAc in hexanes as eluent togive 1.2 g (78%) of7-((2R)-3-methyl-5-(trityloxymethyl)-2,5-dihydrofuran-2-yl)furo[3,2-d]pyrimidin-4-amineas a white solid; mp 128-132° C. (R_(f)=0.67 in 10% MeOH in CHCl₃).

¹H NMR (DMSO-d₆): 8.06 (s, 1H), 7.97 (s, 1H), 7.16-7.37 (m, 17H), 5.77(m, 1H), 5.64(s, 1H), 4.96 (m, 1H), 3.30 (m, 1H), 2.98 (m, 1H), 1.61 (s,3H); IR (KBr): 3328, 1645, 1438, 704 cm⁻¹; MS (ES⁺) 512.32 (M+Na); Anal.Calcd for C₃₁H₂₇N₃O₃.0.5H₂O: C, 74.67; H, 5.66; N, 8.42. Found: C,74.53; H, 5.53; N, 8.25.

Step 6: To a solution of compound from Step 6,7-((2R)-3-methyl-5-(trityloxymethyl)-2,5-dihydrofuran-2-yl)furo[3,2-d]pyrimidin-4-amine(40 mg, 0.082 mmol) in dioxane (4 mL) was added 4N aqueous HCl (0.125mL) at room temperature. The reaction mixture was stirred at roomtemperature for 30 min and the mixture was evaporated, redissolved inMeOH (3 mL) and neutralized with 0.1 N NaOH. The solution was purifiedon a silica gel column using 0 to 10% of MeOH in CHCl₃ to give 12 mg(23%) of desired target,((2S,5R)-5-(4-aminofuro[3,2-d]pyrimidin-7-yl)-4-methyl-2,5-dihydrofuran-2-yl)methanolas a thick oil.

¹H NMR (DMSO-d₆): 8.16 (s, 1H), 8.04 (s, 1H), 5.75-5.79 (m, 1H),5.61-5.65 (m, 1H), 4.90-4.96 (m, 1H), 3.87 (dd, J=12.4 and 2.0 Hz, 1H),3.70 (dd, J=12.4 and 2.8 Hz, 1H) and 1.58 (s, 3H); MS (ES⁺) 248.45(M+H).

Example B-21

2-Amino-7-β-(2′-C-methyl-D-ribofuranosyl)-furo[3,2-d]pyrimidin-4(3H)-one(Scheme B-4)

Steps 1 through 4 were carried out the same way as in Example B-1starting from A-5 instead of A-2.

Step 4 product: ¹H NMR (DMSO-d₆): δ 7.50 (d, J=0.8 Hz, 1H), 7.39-7.25(m, 15H), 5.29 (bs, 2H), 4.88 (1, 1H), 4.64-4.53 (m, 6H), 4.30-4.15 (m,3H), 3.92 (d, J=5 Hz, 1H), 3.73-3.67 (m, 2H), 1.24 (t, 3H), 1.15 (s,3H); IR (KBr) 3462, 3349, 2871, 1705, 1672, 1632, 1591, 1537, 1455,1369, 1323, 1107, 1026 cm⁻¹; MS (ES⁺) 572.31 (M+Na); Anal. Calcd forC₃₄H₃₇NO₇: C, 71.43; H, 6.52; N, 2.45. Found: C, 71.15; H, 6.50; N,2.26.

Step 5: To a solution of product from Step 4 (0.8 g, 1.4 mmol) inpyridine (14 mL) was added triethylamine (0.98 mL, 7 mmol), mercury (II)chloride (0.76 g, 2.8 mmol), 1,3dicarbomethoxy-2-methyl-2-thiopsuedourea (0.58 g, 2.8 mmol) and thereaction mixture was stirred at room temperature overnight. Solvent wasremoved under vacuum and the residue was triturated with ethyl acetate(100 mL) and filtered through a pad of Celite® to remove insolubleimpurities. The filtrate was concentrated under vacuum and the residueobtained was purified by column chromatography (silica gel 40 g, elutingwith 0-75% ethyl acetate in hexanes) to furnish 0.44 g (10%) of desiredproduct as yellow oil.

¹H NMR (DMSO-d₆): δ 11.20 (s, 1H), 9.82 (s, 1H), 7.78 (d, J=0.9 Hz, 1H),7.35-7.22 (m, 15H), 5.25 (s, 1H), 4.60-4.35 (m, 7H), 4.22-4.11 (m, 2H),3.79 (d, J=4.5 Hz, 1H), 3.64 (m, 2H), 3.60 (s, 3H), 3.49 (s, 3H), 1.20(t, 3H), 1.07 (s, 3H); IR (KBr) 3439, 3285, 3152, 2951, 2363, 1810,1734, 1629, 1449, 1409, 1271, 1225, 1184, 1111, 1067, 737, 698 cm⁻¹; MS(ES⁺) 730.42 (M+1); Anal. Calcd for C₃₉H₄₃N₃O₁₁.0.5H₂O: C, 63.39; H,6.01; N, 5.69. Found: C, 63.04; H, 5.94; N, 5.97.

Step 6: To a solution of product from Step 5 (0.4 g, 0.55 mmol) inmethanol (6 mL) was added sodium methoxide (5.4M solution in methanol,0.126 mL) and stirred at room temperature overnight. After 24 h,additional sodium methoxide (5.4M in methanol, 0.126 mL) was added andstirred for 6 h. The reaction was quenched with glacial acetic acid(0.09 mL, 1.5 mmol) and concentrated under vacuum to dryness. Theresidue obtained was purified by column chromatography (silica gel 10 g,eluting with 0-25% CMA-80 in chloroform) to furnish 0.304 g (89%) ofdesired product,2-methoxycarbonylamino-7-(3,4-bis-benzyloxy-5-benzyloxymethyl-3-methyl-tetrahydro-furan-2-yl)-3H-furo[3,2-d]pyrimidin-4-one,as yellow oil.

Step 7: To the product from Step 6 (0.3 g, 0.49 mmol) in methanol (2.5mL) was added 1N NaOH (2.5 mL, 2.5 mmol) and heated at 50° C. for 3 h.Additional 1N NaOH (2.5 mL, 2.5 mmol) was added and continued heating at50° C. for 3 h. The reaction mixture was cooled to room temperature andpH adjusted to 6 using glacial acetic acid (0.3 mL). The reactionmixture was concentrated under vacuum to remove methanol and the yellowsolid obtained was collected by filtration, washed with water and hexaneto furnish 0.25 g (90%) of desired product as a yellow solid; mp 80-84°C.

¹H NMR (DMSO-d₆): δ 11.11 (bs, 1H), 7.89 (s, 1H), 7.38-7.25 (m, 15H),6.38 (bs, 2H), 5.04 (s, 1H), 4.75-4.52 (m, 6H), 4.16-4.11 (m, 1H), 4.05(d, J=7.5 Hz, 1H), 3.80-3.67 (m, 2H), 1.22 (s, 3H); IR (KBr) 3324, 3144,3030, 2897, 2869, 1696, 1643, 1532, 1496, 1453, 1364, 1317, 1099, 1026,cm⁻¹; MS (ES⁺) 568.38 (M+1), (ES⁻): 566.22 (M−1); Anal. Calcd forC₃₃H₃₃N₃O₆.0.5H₂O: C, 68.72; H, 5.95; N, 7.29. Found: C, 68.94; H, 5.75;N, 7.21.

Step 8: A mixture of compound from Step 7 (0.2 g, 0.35 mmol) in ethanol(5 mL) containing Pd—C (10%, 40 mg) and 1N HCl (1.75 mL) washydrogenated at 70 psi for 12 h. The reaction mixture was filteredthrough Celite to remove catalyst and the filtrate was concentratedunder vacuum to dryness. The residue was purified by columnchromatography (silica gel 4 g, eluting with 0-25% methanol inchloroform) to furnish 0.082 g (67%) of desired product as an off-whitesolid.

¹HNMR (DMSO-d₆): δ 11.02 (bs, 1H, D₂O exchangeable), 7.93 (d, J=0.7 Hz,1H), 6.39 (bs, 2H, D₂O exchangeable), 4.96-4.82 (m, 2H, D₂Oexchangeable), 4.81 (d, J=0.7 Hz, 1H), 4.77-4.60 (m, 1H, D₂Oexchangeable), 3.76-3.66 (m, 3H), 3.61-3.53 (m, 1H), 0.94 (s, 3H);¹³CNMR (DMSO-d₆/D₂O): δ 153.75, 147.28, 132.59, 121.66, 82.45, 80.57,78.23, 74.27, 73.92, 61.22, 22.07; IR (KBr) 3381.5, 2926.8 1699.64,1645.5, 1533.4, 1490.0, 1373.3, 1179.2, 1118.7, 1075.0, 1040.3, 881.6,822.0, 781.2, 673.4, 582.5 and 492.1 cm⁻¹; MS (ES⁺) 298.37 (M+1), (ES⁻)296.35 (M−1).

Example B-22

2,4-Diamino-7-β-(2′-C-methyl-D-ribofuranosyl)-furo[3,2-d]pyrimidine(Scheme B-5)

Step 1: To a solution of compound from Example B-21, Step 7 (0.5 g, 0.85mmol) in CH₃CN (5 mL) was added benzyl triethylammonium chloride (0.38g, 1.7 mmol) and N,N dimethylaniline (0.16 mL, 1.28 mmol). After thereaction mixture was heated to 80° C., phosphorus oxychloride (0.5 mL,5.1 mmol) was added and maintained at this temperature for 1 h. Thereaction mixture was concentrated, ice cold water (20 mL) was added toit and was extracted with CHCl₃ (50 mL). The organic layer wasseparated, washed with aqueous sodium bicarbonate solution (2×20 mL) anddried over MgSO₄. After filtration, the filtrate was concentrated andthe residue was purified on a silica gel column using 0 to 10% MeOH inCHCl₃ to give 0.41 g (81%) of the desired product.

MS (ES⁻) 585.20 (M−1).

Step 2: Compound from Step 1 (0.35 g, 0.59 mmol) was taken in a pressurevessel with methanol saturated with ammonia (20 mL) and the vessel washeated to 100° C. for 12 h. After evaporation of the solvent, theresidue was partitioned between CHCl₃ (50 mL) and water (50 mL). Theorganic layer was collected, dried over MgSO₄, filtered and the filtratewas concentrated. The residue was dissolved in EtOH (20 mL) and 10% Pd—C(50 mg) and 1N HCl (0.2 mL) were added to it. The reaction was shakenunder hydrogen atmosphere (70 psi) for 18 h and filtered through Celite.The filtrate was concentrated and the residue was purified on a columnof silica gel using 0 to 50% CMA-50 in CMA-80 to give 81 mg (61%) of thedesired target.

¹H NMR (CD₃OD) δ in ppm 7.60 (s, 1H), 4.80 (s, 1H), 3.85 (m, 1H), 3.75(m, 2H), 3.60 (m, 1H), 0.80 (s, 3H); MS (ES⁺) 297.50 (M+H)⁺.

Example B-23

4-Amino-7-β-(2′-C-ethyl-D-ribofuranosyl)-furo[3,2-d]pyrimidine (SchemeB-6)

This compound was prepared from the product of Example A-8 according tothe procedures used for Example B-20 except at the last step ofdeprotection. The last step of deprotection was achieved throughcatalytic hydrogenation in the presence of 10% Pd—C in ethanolcontaining two equivalents of HCl.

¹H NMR (DMSO-d₆) δ 8.30 (s, 1H), 8.25 (s, 1H), 7.45 (brs, 2H), 5.1 (m,J=5.0 Hz, 1H), 5.00 (m, 1H), 4.50 (m, 1H), 4.12 (m, 3H), 8.80-3.60 (m,3H), 3.10 (m, 1H), 1.20 (m, 2H), 0.70 (t, J=7.1 Hz, 1H); MS (ES⁺) 296.49(M+H)⁺; Anal. Calcd for C₁₃H₁₇N₃O₅.HCl.H₂O: C, 44.68; H, 5.77; N, 12.0.Found: C, 44.78; H, 5.44; N, 11.34.

Example B-24

4-Amino-7-β-(2′-C-methyl-D-ribofuranosyl)-furo[3,2-d]pyrimidine (SchemeB-6)

Step 1: A solution of compound from Example A-3, Step 3 (4.02 g, 8.63mmol) in DMF (45 mL) was treated with t-BuOCH(NMe₂)₂ (12.07 g, 69.25mmol) and stirred at room temperature overnight. The reaction mixturewas diluted with toluene (800 mL) and washed with water (2×400 mL) andbrine (300 mL), and dried over MgSO₄. After filtration the filtrate wasconcentrated to give 5.01 g of the desired product as a light yellowoil, which was used as such for the next step.

Step 2: The product from Step 1 (4.98 g) was dissolved in chloroform(150 mL) and treated with a solution of TFA (2.25 mL) in water (100 mL)and stirred vigorously at room temperature for 17 h. The organic layerwas separated and washed with water (2 x), and dried over MgSO₄. Afterfiltration, the filtrate was concentrated to give 4.26 g of the desiredproduct as light yellow oil, and was used as such for next step.

Step 3: A mixture of compound from Step 2 (1.55 g), 18-crown-6 (0.66 g,2.5 mmol) and KF (365 mg, 6.28 mmol) in DMF (30 mL) was treated dropwisewith chloroacetonitrile (709 mg, 9.39 mmol) followed by stirring at roomtemperature for 14 h (TLC showed that TBDPS group was lost). Afterconcentration, the residue was taken in pyridine (10 mL) and treatedwith trityl chloride (1.35 g, 4.75 mmol) followed by stirring at 70° C.for 19 h. The reaction mixture was diluted with EtOAc (150 mL) andwashed with water (2×70 mL) and brine (70 mL), then dried over MgSO₄.After filtration and concentration of the filtrate, the residue waspurified on a silica gel column using hexanes:ethyl acetate (1:0 to 2:1)as eluent to give 727 mg (43%, three steps) of desired product as amixture of Z, E, α, and β, isomers, as a white foam, which was used assuch for the next step.

MS (ES⁺) 559.30 (M+Na)⁺.

Step 4: A solution of above mixture from Step 3 (520 mg, 0.97 mmol) inTHF (15 mL) was cooled to −78° C. and treated with LDA dropwise (2M inTHF/heptane/ethylbenzene, 1.95 mL, 3.9 mmol) followed by stirring at−78° C. for 2 h. The reaction was quenched with water (320 μL) andstirred at room temperature for 1 h. After concentration, the residuewas purified on a silica gel column using hexanes:ethyl acetate (1:0 to3:1) as eluent to give 15 mg (2.9%) of desired product as a light yellowsyrup.

¹H NMR (CDCl₃): δ 7.50-7.18 (m, 16H), 4.71 (s, 1H), 4.35-4.25 (m, 2H),3.42-3.30 (m, 2H), 1.59 (s, 3H), 1.39 (s, 3H), 1.22 (s, 3H); MS (ES⁺)559.26 (M+Na)⁺.

Step 5: A mixture of compound from Step 4 (23 mg, 0.043 mmol) andformamidine acetate (45 mg, 0.43 mmol) in EtOH (5 mL) was refluxed for23 h. It was then refluxed for five additional days with addition offormamidine acetate (total of 300 mg added, 2.88 mmol, 100 mg every dayfor first three days). The reaction mixture was concentrated andpurified on a silica gel column using chloroform:methanol (1:0 to 95:5)as eluent to give 14 mg (58%) of desired product as a colorless oil.

¹H NMR (MeOH-d₄): δ 8.14 (s, 1H), 7.78 (s, 1H), 7.45-7.37 (m, 6H),7.28-7.10 (m, 9H), 5.07 (s, 1H), 4.20 (d, J=3.0 Hz, 1H), 4.17-4.11 (m,1H), 3.27 (d, J=5.0 Hz, 2H), 1.53 (s, 3H), 1.27 (s, 3H), 1.06 (s, 3H);MS (ES⁺) 586.39 (M+Na)⁺.

Step 6: A solution of compound from Step 5 (14 mg, 0.025 mmol) in MeOH(2 mL) was treated with 20% HCl in MeOH (2.5 mL) and stirred at roomtemperature for 1 h followed by concentration. The residue wasredissolved in a small amount of MeOH and treated with ether toprecipitate the desired compound, which was collected by filtration togive 3 mg (43%) of desired product as hydrochloride.

¹H NMR (MeOH-d₄): δ 8.45 (s, 1H), 8.25 (s, 1H), 5.03 (s, 1H), 4.05-3.81(m, 3H), 3.76 (d, J=7.3 Hz, 1H), 0.96 (s, 3H); MS (ES⁺) 282.41 (M+H)⁺.

Alternate synthesis:

This compound was also prepared from the benzyl protectedtetrahydrofuran derivative:

Step 1: A solution of compound from Example A-4, Step 3 (3.8 g, 6.38mmol) in DMF (50 mL) was treated with t-BuOCH(NMe₂)₂ (4.33 g, 24.86mmol) and stirred at room temperature overnight. The reaction mixturewas diluted with toluene (100 mL) and washed with water (75 mL). Theaqueous phase was extracted further with toluene (50 mL) and thecombined extracts were washed with water (2×) and dried over MgSO₄.After filtration, the filtrate was concentrated to give 5.0 g of thedesired product which was used as such for the next step.

Step 2: The product from Step 1 (4.9 g) was treated with a solution ofTHF/HOAc/H₂O (1:1:1, 30 mL) and stirred at room temperature for 3 h. Thereaction mixture was diluted with chloroform (100 mL) and water (100mL). The organic layer was separated and washed with water (1×), sat.NaHCO₃ (2×), water (1×), and dried over MgSO₄. After filtration, thefiltrate was concentrated to give 3.08 g of the desired product, whichwas used as such for next step.

Step 3: A mixture of product from Step 2 (3.0 g), 18-crown-6 (1.02 g,3.86 mmol) and KF (0.56 g, 4.83 mmol) in DMF (40 mL) was treateddropwise with chloroacetonitrile (1.1 g, 14.49 mmol) followed bystirring at room temperature for 18 h. After concentration, the residuewas taken in EtOAc and filtered through Celite. The filtrate wasconcentrated and the residue was purified on a silica gel column usinghexanes:ethyl acetate (1:0 to 2:1) as eluent to give 1.41 g (33%, threesteps) of desired product (a mixture of Z, E, α, and β isomers) as alight colorless oil, which was used as such for the next step.

MS (ES⁺) 685.25 (M+Na)⁺.

Step 4: A solution of above mixture from Step 3 (817 mg, 1.23 mmol) inTHF (19 mL) was cooled to −78° C. and treated with LDA dropwise (1M inTHF, 4.92 mL) followed by further stirring at −78° C. for 2 h. Thereaction was quenched with water (405 μL) and stirred at roomtemperature for 1 h. After concentration, the residue was purified on asilica gel column using hexanes:ethyl acetate (1:0 to 3:1) as eluent togive 79 mg (9.7%) of desired product as a light yellow syrup.

¹H NMR (CDCl₃): δ 7.42-7.14 (m, 12H), 4.94 (d, J=1.2 Hz, 1H), 4.76-4.50(m, 6H), 4.37-4.29 (m, 1H), 3.95-3.68 (m, 3H), 1.23 (s, 3H); MS (ES⁻)659.68 (M−H)⁻.

Step 5: A mixture of compound from Step 4 (75 mg, 0.113 mmol) andformamidine acetate (300 mg, 2.85 mmol) in EtOH (10 mL) was refluxed for21 h. Additional formamidine acetate (200 mg, 1.90 mmol) was added andit was refluxed again for 19 h. The reaction mixture was concentratedand purified on a silica gel column using chloroform:methanol (1:0 to95:5) as eluent to give 62 mg (80%) of desired product as a light yellowsyrup.

¹H NMR (MeOH-d₄): δ 8.45 (s, 1H), 8.29 (d, J=0.7 Hz, 1H), 7.74-7.40 (m,I 1H), 5.58 (d, J=0.7 Hz, 1H), 5.15-4.79 (m, 6H), 4.55-4.49 (m, 1H),4.44 (d, J=7.6 Hz, 1H), 4.16-4.00 (m, 2H), 1.51 (s, 3H); MS (ES⁺) 710.29(M+Na)⁺.

Step 6: A solution of compound from Step 5 (58 mg, 0.084 mmol) indichloromethane (1.5 mL) was cooled to −78° C. and treated with BCl₃dropwise (1M in dichloromethane, 0.84 mL) followed by stirring at −78°C. for 2 h and at −25° C. for 2.5 h. The reaction mixture was treatedwith CH₂Cl₂/MeOH (1:1, 0.9 mL) and stirred at −15° C. for 0.5 h. It wasthen neutralized with conc. NH₄OH at 0° C. and stirred at roomtemperature for 15 min followed by concentration under vacuum. Theresidue was treated with MeOH (6 mL) and 20% HCl in MeOH (7.5 mL) andstirred at room temperature for 1 h followed by concentration. Theresidue was purified on a silica gel column using chloroform:methanol(1:0 to 3:1) as eluent to give the product, which was treated with MeOH(5 mL) and 20% HCl in MeOH (0.5 mL), then stirred for 10 min. Afterconcentration, the residue was re-dissolved in a small amount of MeOHand treated with ether to precipitate the desired compound as HCl salt.The filtration and washing with ether provided 20 mg (75%) of desiredproduct.

¹H NMR matched with the compound obtained from the previous approach; IR(KBr, cm⁻¹) 3380, 3113, 2693, 1678, 1611, 1079; MS (ES⁺) 304.36 (M+Na)⁺.

Example B-25

4-Amino-7-α-(2′-C-methyl-D-ribofuranosyl)-furo[3,2-d]pyrimidine (SchemeB-6)

Step 1: When Example B-24 was prepared from Example A-3, at Step 4 inthe first approach, another isomer was isolated during chromatography,which corresponded to the alpha isomer (86 mg, 17%).

¹H NMR (CDCl₃): δ 7.48-7.20 (m, 16H), 4.71 (s, 1H), 4.47 (d, J=1.2 Hz,1H), 4.33-4.26 (m, 1H), 3.36-3.22 (m, 2H), 1.48 (s, 3H), 1.42 (s, 3H),1.42 (s, 3H); MS (ES⁺) 559.94 (M+Na)⁺.

Step 2: A mixture of compound from Step 1 (65 mg, 0.12 mmol) andformamidine acetate (130 mg, 99%, 1.24 mmol) in EtOH (5 mL) was refluxedfor 22 h. Additional formamidine acetate (100 mg) was added and thereaction mixture was refluxed for 7 h followed by concentration. Theresidue was purified on a silica gel column using chloroform:methanol(1:0 to 95:5) as eluent to give 60 mg (89%) of desired compound, as alight yellow oil.

¹H NMR (CDCl₃): δ 8.43 (s, 1H), 7.94 (s, 1H), 7.51-7.20 (m, 15H), 5.68(bs, 2H), 5.17 (s, 1H), 4.49 (s, 1H), 4.35 (t, J=6.3 Hz, 1H), 3.38-3.22(m, 2H), 1.52 (s, 3H), 1.49 (s, 3H), 1.39 (s, 3H); MS (ES⁺): 564.49(M+H)⁺.

Step 3: A solution of compound from Step 2 (55 mg, 0.10 mmol) in MeOH (2mL) was treated with 20% HCl in MeOH (2.5 mL) and stirred at roomtemperature for 1 h followed by concentration. The residue wasredissolved in a small amount of MeOH and treated with ether toprecipitate the desired HCl salt, which was collected by filtration togive 19 mg (54%) of desired product as hydrochloride, as yellow solid.

¹H NMR (MeOH-d₄): δ 8.71 (s, 1H), 8.55 (d, J=0.4 Hz, 1H), 5.17 (s, 1H),4.45-4.37 (m, 1H), 4.29 (d, J=8.3 Hz, 1H), 4.12-3.87 (m, 2H), 1.45 (s,3H); IR (KBr, cm⁻¹): 3409, 3132, 1677, 1036; MS (ES⁺) 304.37 (M+Na)⁺.

Example B-26

4-Amino-7-β-(2′-O-methyl-D-ribofuranosyl)-furo[3,2-d]pyrimidine (SchemeB-6)

Step 1: A solution of anomeric isomers from Example A-6, Step 3 (3.07 g,8.36 mmol) in DMF (48 mL) was treated with t-BuOCH(NMe₂)₂ (10 mL, 48.43mmol) and stirred at room temperature for 15 h. The reaction mixture wasdiluted with toluene (300 mL), washed with water (2×150 mL) and brine(150 mL), and dried over MgSO₄. After filtration, the filtrate wasconcentrated to give 3.75 g of desired product as yellow oil, which wasused as such for next step.

MS (ES⁺) 445.48 (M+Na)⁺.

Step 2: The product from Step 1 (3.7 g crude) was dissolved inchloroform (75 mL) and treated with a solution of TFA (1.1 mL) in H₂O(50 mL) followed by vigorous stirring at room temperature for 20 h. Thereaction mixture was diluted with chloroform (75 mL) and was washed withwater (75 mL). The organic layer was separated and dried over MgSO₄.After filtration, the filtrate was concentrated to give 3.67 g ofdesired product as a yellow oil, which was used as such for next step.

MS (ES⁺) 396.45 (M+H)⁺.

Step 3: A mixture of compound from Step 2 (3.62 g), 18-crown-6 (1.78 g,6.73 mmol) and KF (0.97 g, 16.7 mmol) in DMF (75 mL) was treateddropwise with chloroacetonitrile (1.6 mL, 25 mmol) followed by stirringat room temperature for 23 h. The reaction mixture was diluted withEtOAc (200 mL), washed with water (2×100 mL) and brine (100 mL), anddried over MgSO₄. After filtration, the filtrate was concentrated togive 3.24 g of desired product as brown oil, which was used as such fornext step.

MS (ES⁺) 457.40 (M+Na)⁺.

Step 4: A solution of compound from Step 3 (3.19 g) in THF (95 mL) wascooled to −78° C. and treated with LDA (2M in heptane/THF/ethylbenzene,14.5 mL) dropwise followed by stirring at −78° C. for 3 h. The reactionwas quenched with water (2.4 mL) and stirred at room temperature for 1h. After concentration, the residue was purified on a silica gel columnusing hexanes:ethyl acetate (1:0 to 2:1) as eluent to give 863 mg (24%for four steps, R_(f)=0.50, hexanes/EtOAc=2:1) of desired product as abrown oil.

¹H NMR (DMSO-d₆): δ 7.64 (s, 1H), 7.40-7.28 (m, 10H), 5.79 (s, 2H), 4.74(d, J=7.3 Hz, 1H), 4.60-4.46 (m, 4H), 4.20-3.95 (m, 2H), 3.88 (dd,J=7.4, 5.1 Hz, 1H), 3.65-3.45 (m, 2H), 3.30 (s, 3H); MS (ES⁺) 435.44(M+H)⁺.

Step 5: A mixture of compound from Step 4 (404 mg, 0.93 mmol) andformamidine acetate (1.96 g, 18.6 mmol) in EtOH (14 mL) was refluxed for40 h. The reaction mixture was concentrated and purified on a silica gelcolumn using chloroform:methanol (1:0 to 96:4) as eluent to give 317 mg(74%) of desired product as a light brown oil.

¹H NMR (CDCl₃): δ 8.40 (s, 1H), 7.82 (d, J=,0.9 Hz, 1H), 7.36-7.26 (m,10H), 5.54 (bs, 2H), 5.28 (dd, J=3.4, 0.8 Hz, 1H), 4.68-4.49 (m, 4H),4.35-4.28 (m, 1H), 4.22-4.15 (m, 2H), 3.84-3.60 (m, 2H), 3.53 (s, 3H);MS (ES⁺) 462.43 (M+H)⁺.

Step 6: A solution of compound from Step 5 (161 mg, 0.35 mmol) in MeOH(15 mL) was treated with 1N aqueous HCl (1 mL) and Pd—C (10%, 60 mg)followed by hydrogenation (−50 psi) for 6 h. After filtration andconcentration, the residue was purified on a silica gel column usingchloroform/MeOH (1:0 to 4:1) as eluent to give 57 mg (58%) of desiredproduct.

¹H NMR (MeOH-d₄): δ 8.25 (s, 1H), 8.08 (d, J=0.4 Hz, 1H), 5.03 (d, J=8.0Hz, 1H), 4.43 (dd, J=4.9, 2.2 Hz, 1H), 4.18 (dd, J=7.9, 4.9 Hz, 1H),4.12 (dd, J=4.5, 2.2 Hz; 1H), 3.90-3.67 (m, 2H), 3.39 (s, 3H); IR (KBr,cm⁻¹) 3419, 2925, 1656, 1438, 1090; MS (ES⁺) 282.54 (M+H)⁺; Anal. Calcdfor C₁₂H₁₅N₃O₅.0.75 MeOH.0.25H₂O: C, 49.43; H, 6.02; N, 13.56. Found: C,49.02; H, 5.77; N, 13.31.

Example B-27

7-β-(2′-C-Methyl-D-ribofuranosyl)-furo[3,2-d]pyrimidin-4(3H)-thione(Scheme B-7)

Step 1: To a solution of compound from Example B-1, Step 2 (17 g, 35.01mmol) in DMF (250 mL) was added potassium fluoride (4.06 g, 70.02 mmol),18-crown-6 (7.31 g, 27.65 mmol) followed by chloroacetonitrile (7.93 g,105.03 mmol) and the mixture was stirred for 18 h at room temperature.The reaction was diluted with ethylacetate (1 L) and washed with water(2×200 mL), brine (1×200 mL) and dried (MgSO₄). After filtration, thefiltrate was concentrated to afford 16.5 g of desired product, which wasused in the next reaction without further purification.

MS (ES⁺) 525.28 (M+1).

Step 2: To a stirred solution of product from Step 1 (15 g, 28.62 mmol)in THF (450 mL) was added lithiumdiisopropylamide (57.2 mmol, 114.5mmol, 2M solution in THF) at −78° C. over a period of 30 min and stirredfurther at same temperature for 30 min. After quenching the reactionmixture with water (10 mL), it was concentrated and the residue waspurified on a column of silica gel using ethyl acetate:hexanes (0 to20%) as eluent to afford 2.8 g (18.5%) of desired product.

¹H NMR (DMSO-d₆): δ 7.52 (d, J=0.9 Hz, 1H), 7.38-7.26 (m, 15H), 5.63(bs, 2H, D₂O exchangeable), 4.83 (d, J=0.9 Hz, 1H), 4.62-4.54 (m, 6H),4.17 (q, J=4.7 Hz, 1H), 3.89 (d, J=4.9 Hz, 1H), 3.69-3.59 (m, 2H), 1.15(s, 3H); IR (neat): 3446.8, 3344.5, 3233.6, 3063.0, 3031.6, 2977.6,2871.3, 2202.3, 1955.7, 1879.2, 1814.9, 1766.3, 1726.9, 1636.1, 1551.5,1494.8, 1450.5, 1364.0, 1260.6, 1176.7, 1093.6, 1027.6, 912.4, 873.6,819.6, 787.0, 737.7 and 698.3 cm⁻¹; MS (ES⁺) 547.33 (M+23), (ES⁻):523.24 (M−1); Anal. Calcd for C₃₂H₃₂N₂O₅: C, 73.26; H, 6.14; N, 5.33.Found: C, 73.67; H, 6.33; N, 4.90.

Step 3: To a stirred solution of compound from Step 2 (2.8 g, 5.34 mmol)in pyridine (100 mL) was added triethylamine (35 mL) and H₂S gas wasbubbled for 30 min. The reaction mixture was transferred to a steel bomband stirred at 60° C. for 16 h. After concentration, the residue waspurified on a column of silica gel using ethyl acetate:hexanes as eluentto provide 2.35 g (78.8%) of desired product as a yellow brown solid.

¹H NMR (DMSO-d₆): δ 8.48 (bs, 1H, D₂O exchangeable), 8.32 (bs, 1H, D₂Oexchangeable), 7.43 (s, 1H), 7.37-7.25 (15H), 6.46 (bs, 2H, D₂Oexchangeable), 4.89 (s, 1H), 4.65 (m, 6H), 4.17 (dd, J=9.0, 4.3 Hz, 1H),3.92 (d, J=5.3 Hz, 1H), 3.71 (dd, J=10.7, 4.1 Hz, 1H), 3.65 (dd, J=10.7,4.3 Hz, 1H), 1.16 (s, 3H); MS (ES⁺) 559.27 (M+1), 581.23 (M+23).

Step 4: A mixture of product from Step 3 (2.3 g, 4.12 mmol) andtriethylorthoformate (100 mL) was heated at 100° C. for 18 h. Afterconcentration, the residue was purified on a column of silica gel usingethyl acetate:hexanes as eluent to afford 1.32 g (56.5%) of desiredproduct along with some unidentified products.

¹H NMR (DMSO-d₆): δ 14.10 (bs, 1H, D₂O exchangeable), 8.34 (s, 1H), 8.26(s, 1H), 7.38-7.25 (m, 15H), 5.21 (s, 1H), 4.73-4.52 (m, 6H), 4.20-4.15(m, 1H), 4.03 (d, J=7.5 Hz, 1H), 3.79-3.66 (m, 2H), 1.20 (s, 3H); MS(ES⁺) 569.74 (M+1), 591.37 (M+23); Anal. Calcd for C₃₃H₃₂N₂O₅S: C,69.69; H, 5.67; N, 4.92. Found: C, 69.94; H, 5.70; N, 4.88.

Step 5: To a stirred solution of product from Step 4 (0.1 g, 0.176 mmol)in dichloromethane (10 mL) was added BCl₃ (1.7 mL, 1.7 mmol, 1M solutionin dichloromethane) at −78° C. and further stirred at this temperaturefor 30 min and at −30° C. for another 30 min. The reaction was quenchedby adding water (1.5 mL) and brought to room temperature over a periodof 30 min. After neutralization with aqueous NH₃ and concentrating, theresidue was purified on a column of silica gel using methanol andchloroform (0 to 30%) as eluent to afford 10 mg (19%) of product as acolorless solid.

¹H NMR (DMSO-d₆): δ 14.00 (bs, 1H, D₂O exchangeable), 8.39 (s, 1H),8.26, (s, 1H), 5.00 (d, J=4.8 Hz, 1H, D₂O exchangeable), 4.94 (s, 1H),4.82 (t, J=5.4 Hz, 1H, D₂O exchangeable), 4.75 (s, 1H, D₂Oexchangeable), 3.77-3.70 (m, 3H), 3.63-3.54 (m, 1H), 0.92 (s, 3H); MS(ES⁺) 321.26 (M+1), (ES⁻) 297.30 (M+35); Anal. Calcd forC₁₂H₁₄N₂O₅S.0.75H₂O: C, 46.22; H, 5.01; N, 8.98. Found: C, 46.85; H,5.24; N, 8.36.

Example B-28

4-Amino-7-β-(2′-C-methyl-D-ribofuranosyl)-thieno[3,2-d]pyrimidine(Scheme B-8)

Step 1: A solution of compound from Example B-24, Step 2 (1.23 g, 2.49mmol) in dichloromethane (10 mL) at 0° C. was treated with triethylamine(0.44 mL) followed by addition of methyl sulfonyl chloride (343 mg, 3.0mmol) in dichloromethane (6 mL) over a period of 10 min. The reactionmixture was stirred at 0° C. for 1 h and diluted with chloroform (20 mL)and was washed with brine (2×) and dried over MgSO₄. After filtration,the filtrate was concentrated to give desired product (1.43 g) and usedas such for next step.

MS (ES⁺) 594.28 (M+Na)⁺.

Step 2: A mixture of the product from Step 1 (1.43 g),acetylthioacetonitrile (575 mg, 5.0 mmol), and anhydrous Na₂CO₃ (530 mg,5.0 mmol) in absolute ethanol (30 mL) was refluxed for 6 h andconcentrated to dryness. The residue was partitioned between chloroformand water. The organic layer was separated and further washed with waterand dried over MgSO₄. After filtration, the filtrate was concentratedand the residue was purified on a silica gel column using hexanes:ether(1:0 to 7:3) as eluent to give 140 mg (10% for two steps) of desiredproduct as an oil.

¹H NMR (DMSO-d₆): δ 7.54-7.47 (m, 4H), 7.35-7.26 (m, 6H), 7.09 (d, J=1.2Hz, 1H), 5.86 (bs, 2H), 4.53 (s, 1H), 4.30 (d, J=2.3 Hz, 1H), 4.04-3.99(m, 1H), 3.68 (t, J=4.4 Hz, 2H), 1.40 (s, 3H), 1.20 (s, 3H), 0.85 (bs,12H); MS (ES⁺) 571.37 (M+Na)⁺.

Step 3: A mixture of compound from Step 2 (120 mg, 0.22 mmol) andformamidine acetate (227 mg, 2.16 mmol) in EtOH (5 mL) was refluxed for16 h. Additional formamidine acetate (227 mg, 2.16 mmol) was addedfollowed by reflux for 16 h. After concentration, the residue was takenin chloroform and washed with water and dried over MgSO₄. Afterfiltration, the filtrate was concentrated and the residue was purifiedon a silica gel column using hexanes:ether (1:0 to 1:1) as eluent togive 11 mg (9%) of desired product as an oil.

¹H NMR (CDCl₃): δ 8.65 (s, 1H), 7.80-7.70 (m, 4H), 7.64 (d, J=1.2 Hz,1H), 7.50-7.36 (m, 6H), 5.56 (s, 1H), 5.38 (bs, 2H), 4.51 (d, J=3.1 Hz,1H), 4.25 (dd, J=7.2, 3.8 Hz, 1H), 4.00-3.92 (m, 2H), 1.75 (s, 3H), 1.45(s, 3H), 1.12 (s, 3H), 1.10 (s, 9H); MS (ES⁺) 576.49 (M+H)⁺.

Step 4: A solution of compound from Step 3 (28 mg, 0.049 mmol) in 12%dry HCl/MeOH (2 mL) was stirred at room temperature for 0.5 h followedby concentration. The residue was treated with 12% dry HCl/MeOH (2 mL)again and stirred at room temperature for 15 min followed byconcentration. This process was repeated once more with 1 mL of dry 12%HCl/MeOH. The residue was washed with ether (2×) and dried under vacuumto afford 16 mg (88%) of desired product as hydrochloride.

¹H NMR (D₂O): δ 8.45 (s, 1H), 8.18 (s, 1H), 5.14 (s, 1H), 3.98-3.75 (m,4H), 0.80 (s, 3H); MS (ES⁺) 298.41 (M+H)⁺.

Example B-29

4-Amino-7-α-(2′-C-methyl-D-ribofuranosyl)-thieno[3,2-d]pyrimidine(Scheme B-8)

Step 1: Under Example B-28 in Step 2, another product alpha isomer wasalso isolated.

¹H NMR (DMSO-d₆): δ 7.49-7.42 (m, 4H), 7.34-7.20 (m, 7H), 5.99 (s, 2H),4.61 (s, 1H), 4.25 (s, 1H), 3.92 (t, J=6.8 Hz, 1H), 3.59-3.53 (m, 2H),1.19 (s, 3H), 1.15 (s, 3H), 1.12 (s, 3H), 0.83 (s, 9H); IR (neat, cm⁻¹)3473, 3359, 2932, 2858, 2198, 1428, 1109; Anal. Calcd for C₃₀H₃₆N₂O₄Si:C, 65.66; H, 6.61; N, 5.10. Found: C, 65.42; H, 6.68; N, 4.94; MS (ES):571.49 (M+Na)⁺.

Step 2: A mixture of compound from Step 1 (230 mg, 0.42 mmol) andformamidine acetate (437 mg, 4.20 mmol) in EtOH (6 mL) was refluxed for6 h. Additional formamidine acetate (437 mg, mmol) was added followed byreflux for 18 h. The reaction mixture was concentrated and the residuewas taken in chloroform, washed with water, and dried over MgSO₄. Afterfiltration, the filtrate was concentrated and the residue was purifiedon a silica gel column using hexanes:EtOAc (1:0 to 1:1) as eluent togive 195 mg (81%) of desired product as an oil.

¹H NMR (DMSO-d₆): 8.40 (s, 1H), δ 7.99 (s, 1H), 7.78-7.41 (m, 10H), 5.43(s, 1H), 4.63 (s, 1H), 4.24 (t, J=5.5 Hz, 1H), 3.86 (d, J=5.3 Hz, 2H),1.55 (s, 3H), 1.43 (s, 3H), 1.33 (s, 3H), 1.09 (s, 9H); IR (neat, cm⁻¹)3450, 3337, 2932, 2858, 1636, 1573, 1513, 1109; MS (ES⁺) 598.40 (M+Na)⁺;Anal. Calcd for C₃₁H₃₇N₃O₄SSi.H₂O: C, 62.70; H, 6.62; N, 7.08. Found: C,62.40; H, 6.37; N, 6.99.

Step 3: Compound from Step 2 (90 mg, 0.16 mmol) was treated the same wayas Step 4 in Example B-28. It gave 43 mg (74%) of desired product ashydrochloride.

¹H NMR (MeOH-d₄): δ 9.54 (bs, 2H), 8.74 (s, 1H), 8.43 (s, 1H), 5.13 (s,1H), 4.27-4.17 (m, 1H), 4.00 (d, J=8.0 Hz, 1H), 3.76-3.52 (m, 2H), 1.16(s, 3H); IR (KBr, cm⁻¹) 3367, 1661, 1607, 1568, 1036; MS (ES⁺) 298.41(M+H)⁺; Anal. Calcd for C₁₂H₁₅N₃O₄S.HCl.1.5H₂O: C, 39.95; H, 5.31; N,11.65. Found: C, 40.48; H, 5.37; N, 11.24.

Example B-30

7-(2-(Trityloxy)ethyl)furo[3,2-d]pyrimidin-4-amine (Scheme B-6)

It was prepared by following the method (alternate approach, Steps 1-5)used for compound B-24 starting from Example A-1.

¹H NMR (DMSO-d₆): δ 8.18 (s, 1H), 8.02 (s, 1H), 7.32-7.22 (m, 15H), 3.25(t, J=6.6 Hz, 2H), 2.87 (t, J=6.6 Hz, 2H).

Example B-31

(cis)(4-(4-Aminofuro[3,2-d]pyrimidin-7-yl)cyclopent-2-enyl)methanol(Scheme B-6)

It was prepared by following the method used for compound B-24 startingfrom Example A-9.

¹H NMR (CDCl₃): δ 8.42 (s, 1H), 7.58 (s, 1H), 5.89 (td, J=5.4, 2.3 Hz,1H), 5.76 (td, J=5.4, 2.3 Hz, 1H), 5.22 (bs, 2H, D₂O exchangeable), 4.54(bs, 1H, D₂O exchangeable), 4.18-4.10 (m, 1H), 3.88 (dd, J=10.9, 3.7 Hz,1H), 3.76 (dd, J=10.7, 3.0 Hz, 1H), 3.22-3.13 (m, 1H), 2.64 (td, J=13.9,9.7 Hz, 1H), 2.07 (td, J=13.9, 6.4 Hz, 1H); MS (ES⁺) 254.52 (M+23).

Example B-32

(5-(4-Aminofuro[3,2-d]pyrimidin-7-yl)-tetrahydrothiophen-2-yl)methanol(Scheme B-6)

It was prepared by following the method used for compound B-24 startingfrom Example A-10.

¹H NMR (CD₃OD): δ 8.58 (s, 1H), 8.32 (s, 1H), 4.70 (t, J=6.4 Hz, 1H),3.85 (t, J=6.5 Hz, 1H), 3.65 (m, 2H), 2.50 (m, 1H), 2.20 (m, 2H), 1.95(m, 1H); MS (ES⁺) 252.53 (M+H)⁺.

Example B-33

2-(4-Aminofuro[3,2-d]pyrimidin-7-yl)-5-(hydroxymethyl)-3-methylpyrrolidine-3,4-diol(Scheme B-6)

It was prepared by following the method used for compound B-24 startingfrom Example A-11.

¹H NMR (D₂O): 8.58 (s, 1H), 8.53 (s, 1H), 5.05 (s, 1H), 4.51 (d, J=9.2Hz, 1H), 4.10-4.12 (m, 2H), 3.80-3.90 (m, 1H), 1.17 (s, 3H); ¹³C NMR(D₂O): 152.16, 148.59, 147.63, 143.90, 133.77, 113.80, 78.89, 73.45,63.16, 60.67, 57.82, 19.51; MS (ES⁺) 281.41.

Example B-34

2-Amino-7-β-(1)-ribofuranosyl)-furo[3,2-d]pyrimidin-4(3H)-one (SchemeB-4)

It was prepared from Example A-2 by following the same procedure usedfor Example B-21.

¹H NMR (DMSO-d₆): δ 8.11 (s, 1H), 4.69 (d, J=6.9 Hz, 1H), 4.05-4.01 (m,1H), 3.97-3.95 (m, 1H), 3.89-3.86 (m, 1H), 3.80-3.63 (m, 2H); MS (ES⁻)282.34 (M−1). Anal. Calcd for C₁₁H₁₃N₃O₅.2HCl.1.5H₂O: C, 34.55; H, 4.75;N, 10.99. Found: C, 34.37; H, 4.98; N, 10.87.

Example B-35

7-β-(2′-C-Methyl-D-ribofuranosyl)-furo[3,2-d]pyrimidin-4(3H)-one (SchemeB-1)

It was prepared by deprotection of Example B-11 by hydrogenation underthe same conditions used with Example B-16.

¹H NMR (DMSO-d₆): δ 12.42 (bs, 1H, D₂O exchangeable), 8.20 (s, 1H), 8.08(s, 1H), 4.98 (d, J=6.4 Hz, 1H), 4.93 (s, 1H), 4.83 (t, J=5.0 Hz, 1H,D₂O exchangeable), 4.73 (s, 1H, D₂O exchangeable), 3.78-3.70 (m, 2H),3.64-3.54 (m, 1H), 0.93 (s, 3H); MS (ES⁻) 281.34 (M−1); Anal. Calcd forC₁₂H₁₄N₂O₆.CH₄O: C, 49.66; H, 5.77; N, 8.91. Found: C, 49.63; H, 5.61;N, 8.26.

Example C-1

4-Amino-7-β-(2′-C-methyl-D-ribofuranosyl)-furo[3,2-d]pyrimidine-5′-monophosphate(Scheme C-1)

Step 1: A solution of Example B-24 (50 mg, 0.18 mmol) in THF (6 mL) wastreated with 1-H-tetrazole (39 mg, 98%, 0.55 mmol) and cooled withice/water followed by dropwise addition of dibenzylN,N-diisopropylphosphoramidite (75 μL, 0.22 mmol). The reaction mixturewas stirred at 0° C. for 1 h and at room temperature for 2 h. Additionaldibenzyl N,N-diisopropylphosphoramidite (25 μL, 0.075 mmol) was addedand the mixture was stirred at room temperature further for 1 h. Thereaction mixture was cooled to −40° C., and treated with m-CPBA (82 mg,max. 77%) followed by stirring at 0° C. for 2 h. After diluting withchloroform (100 mL), the mixture was washed with 5% Na₂SO₃ (2×30 mL),sat. NaHCO₃ (2×30 mL) and water (2×30 mL), and dried over MgSO₄. Afterfiltration, the filtrate was concentrated and the residue was purifiedon a silica gel column using chloroform/MeOH (1:0 to 10:1) as eluent togive 40 mg (41%) of desired product as a white solid.

¹H NMR (DMSO-d₆): δ 8.22 (s, 1H), 8.10 (s, 1H), 7.39 (bs, 2H), 7.36-7.27(m, 10H), 5.23 (d, J=6.4 Hz, 1H), 5.02 (s, 2H), 5.00 (s, 2H), 4.99 (s,1H), 4.91 (s, 1H), 4.34-4.26 (m, 2H), 4.12-3.96 (m, 2H), 0.92 (s, 3H);MS (ES⁺) 542.31 (M+H)⁺.

Step 2: A mixture of product from Step 1 (35 mg, 0.065 mmol) and Pd—C(10%, 20 mg) in MeOH (15 mL) was hydrogenated for 16 h (˜50 psi).After-removing the catalyst by filtration, the filtrate was concentratedand the residue was treated with water (10 mL) and washed with EtOAc(2×10 mL) and chloroform (2×10 mL). The aqueous phase was concentratedto dryness. The residue was dissolved in 2 mL of H₂O and filtered, whichgave a 24.4 mM (measured by UV at 274 nM) solution of desiredmonophosphate.

¹H NMR (D₂O): δ 8.13 (bs, 1H), 8.03 (s, 1H), 5.03 (s, 1H), 4.20-4.08 (m,1H), 4.06-3.85 (m, 3H), 0.88 (s, 3H); ³¹P NMR (D₂O): δ 0.83 (bs, 1P); MS(ES⁺) 362.42 (M+H)⁺.

Example C-2

2-Amino-7-β-(2′-C-methyl-D-ribofuranosyl)-furo[3,2-d]pyrimidin4(3H)-one-5′-monophosphate (Scheme C-1)

Step 1: A mixture of Example B-21 (48 mg, 0.15 mmol),2,2-dimethoxypropane (0.34 mL, 98%, 2.72 mmol), and p-toluenesulfonicacid monohydrate (40 mg, 0.21 mmol) in acetone (2 mL) and DMF (2 mL) wasstirred at room temperature of 2 h followed by neutralization with 0.5 Naqueous NaOH. The mixture was concentrated to dryness and used as suchfor the next step.

MS (ES⁺) 338.37 (M+H)⁺.

Step 2: The product from Step 1 was mixed with imidazole (60 mg, 0.88mmol) and TBDMSCl (45 mg, 0.30 mmol) in DMF (3 mL) and stirred at roomtemperature for 8 h. Additional imidazole (120 mg) and TBDMSCl (90 mg)were added and the reaction mixture was further stirred at roomtemperature for 17 h followed by concentration to dryness. The residuewas purified on a silica gel column using chloroform/MeOH (1:0 to 95:5)as eluent to give 50 mg (74% for two steps) of desired product as acolorless film.

¹H NMR (MeOH-d₄): δ 7.58 (d, J=1.0 Hz, 1H), 4.91 (s, 1H), 4.29 (d, J=2.9Hz, 1H), 4.02-3.95 (m, 1H), 3.78-3.66 (m, 2H), 1.49 (s, 3H), 1.28 (s,3H), 1.11 (s, 3H), 0.81 (s, 9H), 0.00 (s, 6H); MS (ES⁺) 452.44 (M+H)⁺.

Step 3: A mixture of compound from Step 2 (50 mg, 0.11 mmol) and4-methoxytrityl chloride (70 mg, 0.22 mmol) in pyridine (3 mL) wasstirred at 70° C. for 13 h. The reaction mixture was diluted with EtOAc(100 mL) and washed with water (2×50 mL), brine (50 mL), and dried overMgSO₄. After filtration, the filtrate was concentrated and the residuewas purified on a silica gel column using hexanes/EtOAc (1:0 to 1:1) aseluent to give 45 mg (57%) of desired product as a colorless film.

¹H NMR (CDCl₃): δ 9.91 (bs, 1H), 7.36-7.00 (m, 13H), 6.90 (bs, 1H), 6.68(d, J=8.8 Hz, 2H), 4.72 (s, 1H), 4.23 (d, J=3.2 Hz, 1H), 4.00-3.94 (m,1H), 3.68 (d, J=4.0 Hz, 2H), 3.66 (s, 3H), 1.38 (s, 3H), 1.28 (s, 3H),0.99 (s, 3H), 0.82 (s, 9H), 0.00 (s, 6H);

MS (ES⁺) 746.31 (M+Na)⁺.

Step 4: A solution of product from Step 3 (45 mg, 0.062 mmol) in THF (3mL) was treated with Bu₄NF (1M in THF, 0.12 mL) followed by stirring atroom temperature for 2.5 h. The reaction mixture was concentrated andthe residue was purified on a silica gel column using hexanes/EtOAc/MeOH(1:1:0 to 1:1:0.1) as eluent to give 39 mg (100%) of desired product asa colorless film.

¹H NMR (CDCl₃): δ 7.77 (bs, 1H), 7.60 (s, 1H), 7.40-7.20 (m, 12H), 6.87(d, J=8.9 Hz, 2H), 6.30 (s, 1H), 5.17 (s, 1H), 4.64 (d, J=1.4 Hz, 1H),4.34 (bs, 1H), 4.03-3.68 (m, 2H), 3.80 (s, 3H), 1.60 (s, 3H), 1.41 (s,3H), 1.36 (s, 3H); (MS (ES⁺) 632.28 (M+Na)⁺.

Step 5: A solution of product from Step 4 (39 mg, 0.62 mmol) indichloromethane (2 mL) was treated with 1-H-tetrazole (14 mg, 98%, 0.20mmol) and the suspension was stirred at room temperature for 5 minfollowed by addition of dibenzyl N,N-diisopropylphosphoramidite (35 μL,0.1 mmol). The reaction mixture was stirred at room temperature for 3.5h, cooled to −40° C., and treated with a solution of m-CPBA (30 mg, max.77%) in dichloromethane (1 mL) followed by stirring at 0° C. for 2 h.The reaction mixture was diluted with chloroform (50 mL) and washed with5% Na₂SO₃ (2×15 mL), NaHCO₃ (2×15 mL), water (2×20 mL), and dried overMgSO₄. After filtration, the filtrate was concentrated, and the residuewas purified on a silica gel column using hexanes/EtOAc/MeOH (1:1:0 to1:1:0.1) as eluent to give 38 mg (70% for two steps) of desired productas a white solid.

¹H NMR (DMSO-d₆): δ 10.88 (s, 1H), 7.69 (s, 1H), 7.44-7.10 (m, 23H),6.81 (d, J=8.8 Hz, 2H), 5.06 (s, 2H), 5.03 (s, 2H), 4.51 (s, 1H), 4.12(d, J=2.3 Hz, 1H), 4.05-3.95 (m, 3H), 3.69 (s, 3H), 1.24 (s, 3H), 1.23(s, 3H), 0.81 (s, 3H); IR (KBr, cm⁻¹) 3339, 2984, 1699, 1611, 1252,1017; MS (ES⁺) 870.30 (M+H)⁺; Anal. Calcd for C₄₉H₁₈N₃O₁₀P.0.75H₂O: C,66.62; H, 5.65; N, 4.76. Found: C, 66.68; H, 5.64; N, 4.80.

Step 6: A mixture of product from Step 5 (30 mg, 0.034 mmol) and Pd—C(10%, 20 mg) in MeOH (15 mL) was hydrogenated for 20 h (˜50 psi). Afterremoving the catalyst by filtration, the filtrate was concentrated, andthe residue was treated with TFA (3 mL) and stirred at room temperaturefor 1 h followed by concentration to dryness. The residue was stirredwith EtOAc (20 mL), water (20 mL), and TEAB (pH=8.0, 1M, 2 mL) for 30min. The organic layer was collected, the aqueous phase was furtherextracted with EtOAc (2×20 mL) and the combined organic extracts wereconcentrated to dryness. The residue was treated with MeOH (6 mL) and20% dry HCl in MeOH (7.5 mL) followed by stirring at room temperaturefor 1.2 h. The reaction mixture was concentrated to dryness and purifiedby HPLC (CH₃CN/1M TEAB buffer, pH=8.0, 0-20 min, 0-35% CH₃CN; 20-22 min,35-60% CH₃CN, monitoring at 260 nm) to give the desired product(t_(R)=14.1 min). All the fractions containing product were pooledtogether and reconstituted to 2 mL with water, which gave 6.1 mM(measured by UV at 288 nm)-solution of desired monophosphate.

¹H NMR (D₂O): δ 7.78 (d, J=0.7 Hz, 1H), 4.91 (d, J=0.6 Hz, 1H),4.15-4.07 (m, 1H), 4.04-3.86 (m, 3H), 0.95 (s, 3H); ³¹P NMR (D₂O): 1.81(s, 1P); MS (ES⁺) 378.30 (M+H)⁺.

Example C-3

4-Methylamino-7-β-(2′-C-methyl-D-ribofuranosyl)-furo[3,2-d]pyrimidine-5′-monophosphate(Scheme C-1)

A solution of Example B-17 (50 mg, 0.17 mmol) in THF (5 mL) was cooledto 0° C. and to this were added, tetrazole (0.51 mmol, 35 mg) anddibenzyl diisopropylphosphoramidate (0.17 mmol, 61 μL) and the mixturewas stirred for 1 h. Additional 0.2 equivalents of the phosphorylatingreagents were added and stirring continued for 2 h at room temperature.The reaction was then cooled to −40° C. and m-chloroperbenzoic acid (80mg, 0.34 mmol) was added and the reaction was allowed to warm to roomtemperature. The reaction was quenched by the addition of 10% aqueoussodium sulfite (3 mL), and diluted with CHCl₃ (20 mL). The organic layerwas washed with water (20 mL), aqueous saturated sodium bicarbonatesolution (2×20 mL), and dried over MgSO₄. After filtration, the filtratewas concentrated and the residue was purified on a silica gel columnusing 0 to 5% MeOH in chloroform as eluent to give 70 mg of desiredproduct. This product was dissolved in MeOH (10 mL) and to the solutionwas added 10% Pd—C (50 mg). The suspension was hydrogenated for 18 h at50 psi, the catalyst was removed by filtration through Celite and theresidue was taken in water and ethyl acetate (20 mL each). The organiclayer was removed, and the aqueous layer was concentrated and purifiedby HPLC (gradient 0 to 100% CH₃CN in water on reverse phase C18 column,t_(R)−7.8 min). The desired fractions were collected and concentrated togive 46 mg (70%) of desired phosphate.

¹H NMR (D₂O δ in ppm) 8.05 (s, 1H), 8.04 (s, 1H), 5.20 (s, 1H), 3.90 (m,4H), 2.90 (s, 3H), 0.90 (s, 3H). ³¹P NMR 4.7 ppm. MS (ES⁺) 376 (M+H)⁺,398 (M+Na)⁺, MS (ES⁻) 374.30 (M−H)⁻.

Example C-4

4-Methylamino-7-β-(2′-C-methyl-D-ribofuranosyl)-furo[3,2-d]pyrimidine-5′-triphosphate(Scheme C-2)

Step 1: A mixture of Example B-17 (95 mg, 0.32 mmol), MMTrCl (550 mg,98%, 1.75 mmol), DMAP (25 mg, 0.20 mmol), and pyridine (3.2 mL) in DMF(2 mL) was stirred at room temperature for 19 h followed by addition oftriethylamine (2.4 mL, 17.22 mmol), DMAP (20 mg, 0.16 mmol), and4-nitrobenzoyl chloride (1.22 g, 98%, 6.44 mmol) and stirred at roomtemperature for five days. The reaction mixture was diluted with ethylacetate (100 mL), washed with water (2×50 mL), brine (50 mL), and driedover MgSO₄. After filtration, the filtrate was concentrated and theresidue was purified on a silica gel column using hexanes/EtOAc (1:0 to1:1) as eluent to give 110 mg (34%) of desired product as a brown syrup.

¹H NMR (CDCl₃): δ 8.88 (s, 1H), 7.89 (s, 1H), 8.51-7.20 (m, 24H), 6.85(d, J=9.0 Hz, 2H), 5.95 (d, J=4.0 Hz, 1H), 5.65 (J=0.8 Hz, 1H), 4.27(dd, J=8.0, 4.2 Hz, 1H), 3.80 (s, 3H), 3.76 (s, 3H), 3.66-3.62 (m, 2H),1.48 (s, 3H).

Step 2: A solution of product from Step 1 (105 mg, 0.1 mmol) inacetonitrile (10 mL) was treated with 0.2 N aqueous HCl (0.5 mL) andstirred at room temperature for 2 h. The reaction mixture wasneutralized with 0.5 N aqueous NaOH to pH=5 followed by dilution withwater (20 mL) and concentration to remove most of acetonitrile. Theaqueous mixture was extracted with chloroform (2×50 mL) and EtOAc (2×25mL). The combined organic extracts were dried over MgSO₄. Afterfiltration, the filtrate was concentrated and the residue was purifiedon a silica gel column using hexanes/EtOAc/MeOH (1:0:0 to 1:1:0.1) aseluent to give 600 mg (81%) of desired product as a yellow solid.

¹H NMR (DMSO-d₆): δ 9.13 (s, 1H), 8.46 (d, J=0.8 Hz, 1H), 8.41-7.66 (m,12H), 5.72 (d, J=3.2 Hz, 1H), 5.60 (s, 1H), 5.18 (t, J=6.0 Hz, 1H), 4.25(dd, J=6.8, 3.6 Hz, 1H), 3.85-3.79 (m, 2H), 3.66 (s, 3H), 1.37 (s, 3H);MS (ES⁺): 743.26 (M+H)⁺.

Step 3: A suspension of product from Step 2 (50 mg, 0.067 mmol) in amixture of pyridine (75 μL) and dioxane (220 μL) was treated with afreshly prepared solution of chloro-4H-1,3,2-benzodioxaphosphorin-4-one(1M in dioxane, 80 μL) and was stirred at room temperature for 20 minfollowed by treatment with a solution of tributylammonium pyrophosphate(1.6 Bu₃N.1.0H₄P₂O₇, 51 mg, 0.11 mmol) in DMF (220 μL) and n-butylamine(70 μL) simultaneously. A clear solution formed which was stirred atroom temperature for 30 min and treated with 2.8 mL of 1% I₂ in Py/H₂O(98/2). Excess iodine was reduced by addition of 5% aqueous sodiumthiosulphate (230 μL) and the resulting solution was concentrated todryness. The residue was treated with conc. NH₄OH (20 mL) and wasstirred at room temperature overnight followed by concentration todryness. The residue was dissolved in H₂O (20 mL) and washed with CH₂Cl₂(2×15 mL). The aqueous phase was concentrated under vacuum for a shortperiod of time to remove the trace of CH₂Cl₂ and purified by DEAE ionexchange column chromatography with a linear gradient of TEAB buffer (1MTEAB buffer, pH=8.0/H₂O, 250 mL/250 mL, 0:1 to 1:0). The fractionscontaining the desired nucleotide were combined and concentrated. Theresidue was redissolved in H₂O and purified further by HPLC (CH₃CN/0.1MTEAB buffer, pH=8.0, 0-20 min, 0-35% CH₃CN; 20-28 min, 35-100% CH₃CN,monitoring at 260 nm) to give the product (t_(R)=15.6 min). The desiredfractions were pooled together and re-dissolved in 2 mL of water to give3.3 mM (measured by UV at 278 nm) solution of desired triphosphate.

¹H NMR (D₂O): δ 8.17 (s, 1H), 8.04 (s, 1H), 5.11 (s, 1H), 4.30-4.10 (m,2H), 4.02 (s, 2H), 2.95 (s, 3H), 0.98 (s, 3H); ³¹P NMR (D₂O): 8-8.20 (d,J=17.8 Hz, 1P), −9.86 (d, J=17.3, 1P), −21.50 (t, J=17.9 Hz, 1P); MS(ES⁻) 534.14 (M−1).

Example C-5

4-Amino-7-β-(2′-C-methyl-D-ribofuranosyl)-furo[3,2-d]pyrimidine-5′-triphosphate(Scheme C-2)

Step 1: A mixture of Example B-24 (138 mg, 0.49 mmol) and imidazole (175mg, 2.57 mmol) in DMF (5 mL) was treated with TBDMSCl (130 mg, 0.86mmol) followed by stirring at room temperature for 17 h. To this mixturewere added triethylamine (3.2 mL), DMAP (30 mg, 0.25 mmol),4-nitrobenzoyl chloride (1.66 g, 98%, 8.76 mmol), and DMF (3 mL) andstirring was continued for another 24 h. The reaction mixture wasdiluted with EtOAc (150 mL), washed with water (2×75 mL), brine (75 mL),and dried over MgSO₄. After filtration, the filtrate was concentratedand the residue was purified by column chromatography on a silica gelcolumn using hexanes/ethyl acetate (1:0 to 1:1) as eluent to give 266 mgof product, which was used as such for next step.

MS (ES⁻) 841.47 (M−1).

Step 2: A solution of compound from Step 1 (260 mg) in THF (25 mL) wastreated with tetrabutyl ammonium fluoride (1M in THF, 0.4 mL). Thereaction mixture was stirred at room temperature for 2 h and additionaltetrabutyl ammonium fluoride (1 mL) was added followed by stirring atroom temperature for 5 h and concentration. The residue was purified bycolumn chromatography on silica gel (hexanes/ethyl acetate/methanol,1:1:0 to 1:1:0.1) to give 40 mg (11% for two steps) of desired product.

¹H NMR (DMSO-d₆): δ 11.96 (s, 1H), 9.25 (s, 1H), 8.60 (s, 1H), 8.50-8.17(m, 12H), 5.78 (d, J=3.3 Hz, 1H), 5.71 (s, 1H), 4.30 (m, 1H), 3.89-3.83(m, 2H), 1.52 (s, 3H); MS (ES⁻) 727.58 (M−1).

Step 3: A suspension of product from Step 2 (37 mg, 0.051 mmol) in amixture of pyridine (55 μL) and dioxane (165 μL) was treated with afreshly prepared solution of chloro-4H-1,3,2-benzodioxaphosphorin-4-one(1M in dioxane, 60 μL). The reaction mixture was stirred at roomtemperature for 20 min followed by treatment with a solution oftributylammonium pyrophosphate (1.6 Bu₃N.1.0H₄P₂O₇, 39 mg, 0.082 mmol)in DMF (165 μL) and n-butylamine (55 μL) simultaneously. A clearsolution formed which was stirred at room temperature for 30 minfollowed by treatment with 2.1 mL of 1% I₂ in Py/H₂O (98/2). Excessiodine was reduced by addition of 5% aqueous sodium thiosulphate (175μL) and the resulting solution was concentrated to dryness. The residuewas treated with conc. NH₄OH (15 mL) and was stirred at room temperatureovernight followed by concentration to dryness. The residue wasdissolved in H₂O (20 mL) and washed with CH₂Cl₂ (2×15 mL). The aqueousphase was concentrated under vacuum for a short period of time to removethe trace of CH₂Cl₂ and purified by DEAE ion exchange columnchromatography with a linear gradient of TEAB buffer (1M TEAB buffer,pH=8.0/H₂O, 0:1 to 1:0). The fractions containing the desired nucleotidewere combined and concentrated and the residue was redissolved in H₂Oand purified further by HPLC (CH₃CN/0.1M TEAB buffer, pH=8.0, 0-20 min,0-35% CH₃CN; 20-28 min, 35-100% CH₃CN, monitoring at 260 nm) to givedesired triphosphate (t_(R)=14.7 min). The fractions containing desiredproduct were pooled together, concentrated and re-dissolved in 2 mL ofwater to give 1.38 mM (measured by UV at 274 nM) solution oftriphosphate.

¹H NMR (D₂O): δ 8.15 (s, 1H), 8.09 (s, 1H), 5.12 (s, 1H), 4.29-4.10 (m,2H), 4.02 (bs, 2H), 0.97 (s, 3H); ³¹P NMR (D₂O): 6-8.50 (d, J=15.8 Hz,1P), −9.88 (d, J=16.8, 4.5 Hz, 1P), −21.5 (dd, J=15.8, 16.8 Hz, 1P); MS(ES⁻) 520.53 (M−1).

Example C-6

(2-(4-Aminofuro[3,2-d]pyrimidin-7-yl)ethoxy)methylphosphonic acid(Scheme C-3)

Step 1: To a stirred solution of compound from Example B-30,7-(2-trityloxyethyl)-furo[3,2-d]pyrimidin-4-ylamine (0.52 g, 1.23 mmol)in pyridine (20 mL) was added triphenylchloromethane (0.68 g, 2.46 mmol)at room temperature and the mixture was stirred at 70° C. for 16 h.Additional triphenylchloromethane (6.8 g, 24.6 mmol) was added and againstirred at 70° C. for 48 h. To the reaction mixture was added MeOH (50mL) and stirred for 1 h at 70° C. The reaction mixture was concentratedand the residue was dissolved in chloroform (100 mL), washed with water(2×50 mL), brine (50 mL), and dried (MgSO₄). After filtration, thefiltrate was concentrated and the residue was purified on a silica gelcolumn using ethyl acetate in hexanes (0 to 50%), which afforded 0.788 g(96.5%) of desiredtrityl-[7-(2-trityloxyethyl)-furo[3,2-d]pyrimidin-4-yl]-amine, as acolorless solid.

¹H NMR (DMSO-d₆): δ 8.20 (s, 1H, D₂O exchangeable), 8.09 (s, 1H), 7.88(s, 1H), 7.70-7.14 (m, 30H), 3.22 (t, J=6.6 Hz, 2H), 5.87 (t, J=6.4 Hz,2H); MS (ES⁺) 664.64 (M+1).

Step 2: A solution of compound from Step 1 (753 mg, 1.13 mmol) inacetonitrile (130 mL) was treated with aqueous 0.2 N HCl (6.5 mL, 1.3mmol) followed by stirring at room temperature for 8 h. The reactionmixture was neutralized with aqueous 0.5 N NaOH, diluted with 150 mL ofwater, and concentrated under vacuum to remove most of the acetonitrile.The aqueous residue was extracted with chloroform (200 mL) and ethylacetate (200 mL, 100 mL). The combined organic extracts were dried overMgSO₄. After filtration and concentration, the residue was purified on asilica gel column using hexanes:ethyl acetate:methanol (1:1:0 to1:1:0.1) as eluent to give 394 mg (83%) of desired product as a whitesolid.

¹H NMR (DMSO-d₆): δ 8.18 (s, 1H), 8.04 (s, 1H), 7.95 (s, 1H), 7.40-7.14(m, 15H), 4.80 (t, J=5.5 Hz, 1H), 3.72-3.62 (m, 2H), 2.72 (t, J=6.8 Hz,2H); MS (ES⁺) 422.43 (M+H)⁺.

Step 3: A solution of product from Step 2 (345 mg, 0.82 mmol) in DMF (7mL) was treated with sodium hydride (60%, 132 mg, 3.3 mmol) at roomtemperature and the mixture was stirred for 1 h. To this solution wasadded a solution of (di-isopropoxyphosphono)methyl tosylate (345 mg,0.98 mmol) in DMF (1 mL) and the mixture was stirred at room temperaturefor 18 h. The reaction mixture was diluted with ethyl acetate (100 mL),neutralized with acetic acid and washed with water (2×) and brine andthe organic layer was dried over MgSO₄. After filtration, the filtratewas concentrated and the residue was purified on a silica gel columnusing ethyl acetate:hexanes:methanol (1:1:0 to 1:1:0.1), then CMA-80 aseluents to give 160 mg (33%) of desired product as a colorless film.

MS (ES⁺) 622.43 (M+Na)⁺.

Another compound with loss of one isopropyl group, 170 mg (37%) wasisolated as a white solid.

MS (ES⁺) 558.43 (M+H)⁺.

The mixture of both compounds was used for the next step.

Step 4: A solution of products from Step 3, (139 mg, 0.23 mmol) and (142mg, 0.25 mmol), in DMF (4.8 mL) was treated with triethylamine (0.42 mL)followed by trimethylsilyliodide (0.69 mL, 4.83 mmol) and the reactionmixture flask was covered with aluminum foil to protect from light andstirred for 24 h at room temperature. It was then diluted with TEABbuffer (13 mL), water (50 mL) and chloroform (85 mL) and stirred for 1h. The organic phase was collected and the aqueous phase wasre-extracted with chloroform (3×50 mL). The combined organic extractswere dried over MgSO₄. After filtration, the filtrate was concentratedand the residue was used as such for next step.

MS (ES⁺) 516.40 (M+H)⁺.

Step 5: A solution of compound from Step 4 in MeOH (21 mL) was treatedwith conc. HCl (21 mL) and stirred at room temperature for 20 h. Thereaction mixture was concentrated to dryness and treated with 10 mL ofwater followed by extraction with ethyl acetate (2×10 mL). The aqueouslayer was concentrated to about 5 mL, filtered (0.2 μm), and purified byHPLC (CH₃CN/0.1 M TEAB buffer, pH=8.0, 0-20 min, 0-35% CH₃CN; 20-28 min,35-100% CH₃CN, monitoring at 260 nm) to give the desired product(t_(R)=14.74 min). Fractions containing the desired product were pooledtogether, concentrated and re-dissolved in 2 mL of H₂O and give 10.48 mM(measured by UV at 274 nm) solution of the monophosphate.

¹H NMR (H₂O-d₂): δ 8.10 (s, 1H), 7.78 (s, 1H), 3.74 (t, J=6.2 Hz, 2H),3.53 (d, J=8.5 Hz, 2H), 2.79 (t, J=6.2 Hz, 2H); ³¹P NMR (H₂O-d₂): 17.02(bs, 1P); MS (ES⁺): 274.46 (M+H)⁺.

Example D-1

Methyl2-(((5-(4-aminofuro[3,2-d]pyrimidin-7-yl)-3,4-dihydroxy-4-methyl-tetrahydrofuran-2-yl)methoxy)(phenoxy)phosphorylamino)-3-methylbutanoate(Scheme D-1)

Step 1: To a solution of POCl₃ (10 mL, 107 mmol) in CH₂Cl₂ (30 mL) at−50° C. (dry ice/acetone) was added a solution of phenol (2.86 g, 30.3mmol) and Et₃N (4.25 mL, 30.4 mmol) in CH₂Cl₂ (25 mL) over a period of15 min. The temperature was allowed to go to 10° C. over a period of 1.5h and stirred at room temperature overnight. The white solid was removedby filtration under nitrogen atmosphere and the filtrate was evaporatedto dryness. To the residue, Et₂O (20 mL) was added and the white solidwas removed again by filtration. The concentration of the filtrateprovided 8.1 g of phenyl phosphorodichloridate, which was used as suchfor the next step.

Step 2: To a solution of L-valine-methyl ester hydrochloride (2.4 g,14.36 mmol) and phenyl phosphorodichloridates from Step 1 (3.02 g) inCH₂Cl₂ (60 mL) at −78° C. (dry ice/acetone) was added a solution of Et₃N(4.02 mL, 28.72 mmol) in CH₂Cl₂ (20 mL) over a period of 30 min. Thereaction mixture was further stirred at −50 to −30° C. for 4.5 h andthen evaporated to dryness. To the residue was added Et₂O (20 mL) andthe white solid was removed under nitrogen. The filtrate wasconcentrated to give 3.0 g (68%) of phenyl methylvalinephosphorochloridate, which was used as such for the next step.

Step 3: To a solution of Example B-24 (63 mg, 0.225 mmol) and N-methylimidazole (74 mg, 0.9 mmol) in THF (1 mL) was added a solution ofphosphorochloridate from Step 2 (137 mg, 0.45 mmol) in THF (1 mL) atroom temperature and the mixture was stirred for 4 h. Additionalphosphorochloridate (137 mg, 0.45 mmol) and N-methyl imidazole (74 mg,0.9 mmol) were added and stirred for 17 h at room temperature. Thereaction mixture was concentrated and the residue was purified on acolumn of silica gel using 0 to 5% MeOH in CHCl₃ to give 28 mg (23%) ofdesired product as a white solid, mp 58-62° C.

¹H NMR (DMSO-d₆): 8.23 (s, 1H), 8.08 (s, 1H), 7.00-7.40 (m, 7H),5.85-6.00 (m, 1H), 5.17 (brs, 1H, D₂O exchangeable), 4.99 and 4.97 (2s,1H), 4.89 (brs, 1H, D₂O exchangeable), 3.92-4.35 (m, 3H), 3.66 and 3.57(2s, 3H), 3.33-3.68 (m, 2H), 1.78-1.96 (m, 1H), 0.92 (s, 3H), 0.80 (d,J=6.8 Hz, 3H) and 0.73 (d, J=6.8 Hz, 3H); IR (KBr) 3341, 3205, 2965,1739, 1653, 1491, cm⁻¹; MS (ES⁺) 573.30 (M+Na); Anal. Calcd forC₂₄H₃₁N₄O₉P.2H₂O: C, 49.14; H, 6.01; N, 9.55. Found: C, 49.24; H, 5.78;N, 9.33.

Example D-2

Methyl2-(((5-(4-Aminofuro[3,2-d]pyrimidin-7-yl)-3,4-dihydroxy-4-methyl-tetrahydrofuran-2-yl)methoxy)(phenoxy)phosphorylamino)propanoate(Scheme D-1)

This compound was prepared the same way as Example D-1 except thatL-alanine-methyl ester hydrochloride was used in this preparationinstead of L-valine-methyl ester hydrochloride, yield (48%).

¹H NMR (DMSO-d₆): 8.24 and 8.23 (2s, 1H, for both isomers), 8.08 and8.07 (2s, 1H, both isomers), 7.10-7.40 (m, 7H, ArH and NH₂), 5.94-6.00(m, 1H), 5.14-5.20 (m, 1H), 4.96 and 4.99 (2s, 1H), 4.90 (s, 1H),4.14-4.35 (m, 2H), 3.94-4.02 (m, 2H), 3.78-3.89 (m, 1H), 3.52 and 3.56(2s, 3H), 1.15 and 1.23 (2d, J=7.34 and 6.94 Hz, 3H), 0.92 (s, 3H); IR(KBr): 3335, 3201, 1741, 1653, 1489, 1213, 935 cm⁻¹; MS (ES⁺) 545.28(M+Na); Anal. Calcd for C₂₂H₂₇N₄O₉P.0.75H₂O: C, 49.30; H, 5.35; N,10.45. Found: C, 49.51; H, 5.18; N, 9.94.

Example D-3

S,S′-2,2′-(((5-(4-Aminofuro[3,2-d]pyrimidin-7-yl)-3,4-dihydroxy-4-methyl-tetrahydrofuran-2-yl)methoxy)phosphoryl)bis(oxy)bis(ethane-2,1-diyl)bis(2,2-dimethylpropanethioate)(Scheme D-2)

To a solution of Example B-24 (0.16 g, 0.6 mmol) in THF (20 mL) at 0° C.were added tetrazole (120 mg, 1.8 mmol) and 2,2-dimethyl-thiopropionicacidS-{diisopropylamino-[2-(2,2-dimethyl-propionylsulfanyl)-ethoxy]-phosphanyloxymethyl}ester(0.51 g, 1.2 mmol) dropwise followed by stirring for 2 h at roomtemperature. After the reaction mixture was cooled to −40° C., 70%m-chloroperbenzoic acid (0.27 g, 0.7 mmol) was added and the reactionwas allowed to warm to room temperature and was quenched by the additionof aqueous 10% sodium sulfite (3 mL) and diluted with CHCl₃ (20 mL). Theorganic layer was washed with water (20 mL), aqueous saturated sodiumbicarbonate solution (2×20 mL) and dried over MgSO₄. After filtration,the filtrate was concentrated and the residue was purified on a silicagel column using 0 to 10% MeOH in chloroform as eluent to give 90 mg(20%) of desired product.

¹H NMR (DMSO-d₆ δ in ppm) 8.25 (s, 1H), 8.15 (s, 1H), 7.40 (br s, 2H),5.20 (m, 1H), 4.90 (m, 2H), 4.20 (m, 2H), 4.00 (m, 6H), 3.10 (m, 4H),1.15 (m, 18H), 0.90 (s, 3H); ³¹P NMR 0.68 ppm; MS (ES⁺) 650.32 (M+H)⁺;Anal. Calcd for C₂₆H₄₀N₃O,₀PS₂: C, 48.05; H, 6.20; N, 6.47. Found: C,48.02; H, 6.37; N, 6.23.

Example D-4

S,S′-2,2′-(((5-(4-Aminofuro[3,2-d]pyrimidin-7-yl)-3,4-dihydroxy-4-methyl-tetrahydrofuran-2-yl)methoxy)phosphoryl)bis(oxy)bis(ethane-2,1-diyl)diethanethioate(Scheme D-2)

This compound was prepared the same way as Example D-3 using, compoundfrom Example B-24 and thioacetic acidS-{2-[(2-acetylsulfanyl-ethoxy)-diisopropylaminophosphanyloxy]-ethyl}ester,yield 8.6 mg (3%).

¹H NMR (DMSO-d₆ δ in ppm) 8.26 (s, 1H), 8.12 (s, 1H), 7.35 (br s, 2H),5.20 (m, 1H), 4.95 (m, 2H), 4.30 (m, 2H), 4.00 (m, 6H), 3.20 (m, 4H),2.30 (m, 6H), 0.90 (s, 3H); ³¹P NMR 0.61 ppm; MS (ES⁺) 566.28 (M+H)⁺.

Example D-5

S,S′-2,2′-(((3,4-Dihydroxy-5-(4-methoxyfuro[3,2-d]pyrimidin-7-yl)₄-methyl-tetrahydrofuran-2-yl)methoxy)phosphoryl)bis(oxy)bis(ethane-2,1-diyl)bis(2,2-dimethylpropanethioate)(Scheme D-2)

This compound was prepared the same way as Example D-3 using compoundfrom Example B-13 and 2,2-dimethyl-thiopropionic acidS-{diisopropylamino-[2-(2,2-dimethyl-propionylsulfanyl)-ethoxy]-phosphanyloxymethyl}ester,yield 15 mg (13%).

¹H NMR (CDCl₃ δ in ppm) 8.60 (s, 1H), 7.90 (s, 1H), 5.20 (m, 1H), 4.40(m, 3H), 4.25 (s, 3H), 4.20 (m, 6H), 3.90 (m, 1H), 3.20 (m, 4H), 1.20(m, 18H), 1.00 (s, 3H); ³¹P NMR 0.0 ppm; MS (ES⁺) 665.28 (M+H)⁺, MS(ES⁻) (M+Cl)⁻ 699.19.

Example D-6

S,S′-2,2′-(((3,4-Dihydroxy-4-methyl-5-(4-(methylamino)furo[3,2-d]pyrimidin-7-yl)-tetrahydrofuran-2-yl)methoxy)phosphoryl)bis(oxy)bis(ethane-2,1-diyl)bis(2,2-dimethylpropanethioate)(Scheme D-2)

This compound was prepared the same way as Example D-3 using compoundfrom Example B-17 and 2,2-dimethyl-thiopropionic acidS-{diisopropylamino-[2-(2,2-dimethyl-propionylsulfanyl)-ethoxy]-phosphanyloxymethyl}ester,yield 107 mg (48%).

¹H NMR (DMSO-d₆ δ in ppm) 8.35 (s, 1H), 8.00 (s, 1H), 7.80 (br s, 1H),5.20 (d, J=6.5 Hz, 1H), 4.97 (m, 1H), 4.90 (m, 1H), 4.26 (m, 2H), 3.99(m, 6H), 3.00 (m, 4H), 2.96 (m, 3H), 1.14 (m, 18H), 0.91 (s, 3H); ³¹pNMR 0.60 ppm; MS (ES⁺) 686.27 (M+Na)⁺, MS (ES⁻) (M−H)⁻ 662.30; Anal.Calcd for C₂₇H₄₂N₃O₁₀PS₂: C, 47.24; H, 6.54; N, 6.12. Found: C, 47.16;H, 6.27; N, 6.10.

Example D-7

S,S′-2,2′-((5-(2-Amino-4-oxo-3,4-dihydrofuro[3,2-d]pyrimidin-7-yl)-3,4-dihydroxy-4-methyl-tetrahydrofuran-2-yl)methoxy)phosphoryl)-bis(oxy)bis(ethane-2,1-diyl)bis(2,2-dimethylpropanethioate)(Scheme D-2)

This compound was prepared the same way as Example D-3 using compoundfrom Example B-21 and 2,2-dimethyl-thiopropionic acidS-{diisopropylamino-[2-(2,2-dimethyl-propionylsulfanyl)-ethoxy]-phosphanyloxymethyl}ester,yield 28 mg (33%).

¹H NMR (DMSO-d₆ δ in ppm) 10.90 (br s, 1H), 7.80 (s, 1H), 6.30 (br s,2H), 5.12 (m, 1H), 4.80 (m, 2H), 4.20 (m, 2H), 4.00 (m, 4H), 3.80 (m,2H), 3.00 (m, 4H), 1.12 (m, 18H), 0.91 (s, 3H); ³¹P NMR 0.50 ppm; MS(ES⁺) 666.36 (M+H)⁺, MS (ES⁻) (M−H)⁻ 664.33.

Example D-8

The following illustrate representative pharmaceutical dosage forms,containing a compound of formula I, II, or III, or a pharmaceuticallyacceptable salt or prodrug thereof (‘Compound X’), for therapeutic orprophylactic use in humans. (i) Tablet 1 mg/tablet Compound X = 100.0Lactose 77.5 Povidone 15.0 Croscarmellose sodium 12.0 Microcrystallinecellulose 92.5 Magnesium stearate 3.0 300.0 (ii) Tablet 2 mg/tabletCompound X = 20.0 Microcrystalline cellulose 410.0 Starch 50.0 Sodiumstarch glycolate 15.0 Magnesium stearate 5.0 500.0 (iii) Capsulemg/capsule Compound X = 10.0 Colloidal silicon dioxide 1.5 Lactose 465.5Pregelatinized starch 120.0 Magnesium stearate 3.0 600.0 (iv) Iniection1 (1 mg/ml) mg/ml Compound X = (free acid form) 1.0 Dibasic sodiumphosphate 12.0 Monobasic sodium phosphate 0.7 Sodium chloride 4.5 1.0 NSodium hydroxide solution q.s. (pH adjustment to 7.0-7.5) Water forinjection q.s. ad 1 mL (v) Iniection 2 (10 mg/ml) mg/ml Compound X =(free acid form) 10.0 Monobasic sodium phosphate 0.3 Dibasic sodiumphosphate 1.1 Polyethylene glycol 400 200.0 01 N Sodium hydroxidesolution q.s. (pH adjustment to 7.0-7.5) Water for injection q.s. ad 1mL (vi) Aerosol mg/can Compound X = 20.0 Oleic acid 10.0Trichloromonofluoromethane 5,000.0 Dichlorodifluoromethane 10,000.0Dichlorotetrafluoroethane 5,000.0The above formulations may be obtained by conventional procedures wellknown in the pharmaceutical art.

All publications, patents, and patent documents are incorporated byreference herein, as though individually incorporated by reference. Theinvention has been described with reference to various specific andpreferred embodiments and techniques. However, it should be understoodthat many variations and modifications may be made while remainingwithin the spirit and scope of the invention.

1. The compound4-Amino-7-β-(2′-C-methyl-D-ribofuranosyl)-furo[3,2-d]pyrimidine; or apharmaceutically acceptable salt or prodrug thereof. 2-31. (canceled)32. The compound of claim 1 which is a prodrug.
 33. The compound ofclaim 32 which comprises one or more mono-, di-, or tri-phosphategroups.
 34. The compound of claim 32 which comprises one or moremono-phosphate groups.
 35. (canceled)
 36. The compound of claim 33wherein one or more pendent hydroxyl groups from the mono-, di-, ortri-phosphate group has been converted to an alkoxy, substituted alkoxy,aryloxy, or substituted aryloxy group.
 37. The compound of claim 33wherein one or more pendent hydroxyl groups from the mono-, di-, ortri-phosphate group has been converted to a group R_(y)—O—; wherein eachR_(y) is independently a 1-20 carbon branched or unbranched, saturatedor unsaturated chain, wherein one or more of the carbon atoms isoptionally replaced with —O— or —S— and wherein one or more of thecarbon atoms is optionally substituted with oxo (═O) or thioxo (═S). 38.The compound of claim 33 wherein one or more pendent hydroxyl groupsfrom the mono-, di-, or tri-phosphate group has been converted to agroup R_(z)—N—; wherein each R_(z) is a residue of an amino acid. 39.The compound of claim 38 wherein the amino acid is a natural amino acid.40. The compound of claim 33 which comprises one or more groups offormula:

wherein: R₁₅ is H, alkyl, substituted alkyl, aryl, substituted aryl,cycloalkyl, substituted cycloalkyl, heteroaryl, substituted heteroaryl,heterocyclic, substituted heterocyclic, or an amino acid; R₁₆ is H,optionally substituted monocyclic aryl, or optionally substitutedmonocyclic heteroaryl; and R₁₇ is H, halogen, CN, —CO—R₂₀, —CON(R₂₁)₂,—CO₂R₂₀, —SO₂R₂₀, —SO₂N(R₂₁)₂, —OR₂₁, —SR₂₁, —R₂₁, —N(R₂₁)₂, —O—COR₂₀,—O—CO₂R₂₀, —SCOR₂₀, —S—CO₂R₂₀, —NHCOR₂₁, —NHCO₂R₂₁, —(CH₂)_(p)—OR₂₂, or—(CH₂)_(p)—SR₂₂; or R₁₆ and R₁₇ are connected via an additional 3-5atoms to form a cyclic group, optionally containing one heteroatom, thatis fused to an aryl group at the beta and gamma position to the Oattached to the phosphorus; or R₁₇ and R₁₈ are connected as describedbelow; R₁₈ and R₁₉ are each independently H, alkyl, aryl,heterocycloalkyl, aralkyl, optionally substituted monocyclic aryl oroptionally substituted monocyclic heteroaryl; or R₁₈ and R₁₉ areconnected via an additional 2-5 atoms to form a cyclic group, optionallycontaining 0-2 heteroatoms; or R₁₇ and R₁₈ are connected via anadditional 3-5 atoms to form a cyclic group, optionally containing oneheteroatom and R₁₉ is H, alkyl, aryl, heterocycloalkyl, aralkyl,optionally substituted monocyclic aryl or optionally substitutedmonocyclic heteroaryl; R₂₀ is alkyl, aryl, heterocycloalkyl, orarylalkyl; R₂₁ is H, alkyl, aryl, heterocycloalkyl, or arylalkyl; R₂₂ isH or lower acyl; n is an integer from 2-5; m is an integer from 10-20;and p is an integer from 2-3.
 41. A pharmaceutical compositioncomprising a compound as described in claim 1; or a pharmaceuticallyacceptable salt or prodrug thereof and a pharmaceutically acceptablecarrier.
 42. The composition of claim 41 which further comprises one ormore additional anti-viral agents.
 43. The composition of claim 42wherein the one or more anti-viral agents are selected from ribavirin,levovirin, viramidine, thymosin alpha-1, an inhibitor of a serineproteases, an inhibitor of inosine monophosphatedehydrognease,interferon-α, and pegylated interferon-α (peginterferon-α).
 44. Thecomposition of claim 41 which further comprises one or more additionalHCV polymerase inhibitors.
 45. The composition of claim 41 which furthercomprises one or more protease inhibitors.
 46. The composition of claim41 which further comprises ribavirin.
 47. The composition of claim 41which further comprises interferon-α or pegylated interferon-α(peginterferon-α).
 48. (canceled)
 49. (canceled)
 50. A method fortreating a viral infection in an animal comprising administering to theanimal an effective amount of a compound as described in claim 1; or apharmaceutically acceptable salt or prodrug thereof.
 51. The method ofclaim 50 wherein the viral infection is selected from the groupconsisting of: hepatitis B, hepatitis C, human immunodeficiency virus,Polio, Coxsackie A and B, Rhino, Echo, small pox, Ebola, and West Nilevirus.
 52. The method of claim 50 wherein the viral infection is HCV.53. The method of claim 50 which further comprises administering to theanimal one or more additional HCV polymerase inhibitors.
 54. The methodof claim 50 which further comprises administering to the animal, one ormore protease inhibitors.
 55. The method of claim 50 which furthercomprises administering ribavirin to the animal.
 56. The method of claim50 which further comprises administering interferon-α or pegylatedinterferon-α (peginterferon-α) to the animal.
 57. (canceled) 58.(canceled)
 59. The method of any one of claim 50 wherein the animal is ahuman.
 60. A method for inhibiting a viral RNA or DNA polymerasecomprising contacting the polymerase in vitro or in vivo with aneffective inhibitory amount of a compound as described in claims 1; or apharmaceutically acceptable salt or prodrug thereof.
 61. The method ofclaim 60 wherein the viral polymerase is an RdRp.